Here are some pics.

http://s1235.photobucket.com/albums/ff436/atata5050/?albumview=slideshow

My dad stepped on it, now it has wrinkles :( :( :(, can it still survive? Or is it shrivelling because of sunlight exposure

That's a nice one. Rather overwatered, which isn't unusual for box store Lithops.

If it's just wrinkled it should be fine. What you need to avoid is damage to the meristem, which is the tiny growing point within the plant, above the stem. Everything else goes away when the leaves do. :) But post a pic anyway, meristem damage takes a while to show because the plant does so much of its growing where you can't see it.

At this time of year they should be gearing up to flower, and mine is happily expanding its root system. Attached is a picture of it. There's a thin taproot under there somewhere.

1. When do I water my plant and how much?
As a starting point -- mostly in the spring, a little in the autumn, dry at other times. There's a lot written on the net about the watering of Lithops, and a lot of it is dependent on your soil mix and local climate. They're highly seasonal plants, and they like to do the exact same thing each year -- grow a flower bud within the plant, flower, grow their new leaves within the body, push the new leaves out, eat the old ones, repeat. It's better to underwater than overwater. If overwatered, Lithops will happily suck up water until they burst, are prone to growing very tall and 'flabby', and grow a stack of misshapen leaves because they're getting water from the roots and not from the old leaves. All of this is fixable so long as the plant doesn't rot.

2. Can I make with the soil needed to grow this plant at home?
Don't quite understand what you've written, but the plant certainly won't be happy with what it's in now. Lithops don't like a lot of organic matter. Check the net for recipes, again this is dependent on your local climate. If you need to be rough to get the roots bare, the fine roots are expendable. The plant has its own water store and can regrow roots from the larger central root, which you shouldn't damage.

3. What exactly is meant by ventilation?
Air flow. These plants can literally boil because they photosynthesise by catching the sun within their bodies, and without a way to get rid of the heat they fry like a badly-ventilated CPU. In nature they'd sit with their windows level with the ground and allow the soil to cool them off, but normally in cultivation there's too much moisture and too little sun to make this work.

4. Is it possible to grow several Lithops, if I only have one Lithops plant.
Some of them might or might not be self fertile, if you want seed. If you just want more plants, in time the head will divide. What'll happen is that instead of two new semicircular leaves emerging at right angles to the old ones, you'll get four new blobs that will reshape themselves next year when they have enough room to grow correctly. Eventually both heads will get their own section of stem, and they can be separated and rooted. You won't get seed if you weren't before, as they're still genetically identical.

Here is a link that might be useful: {{gwi:645918}}

Oh thanks a lot man for helping me out! Is the pot big enough to support my plant. Also the soil was by default like this when I bought it. Any suggestions?

Here is the link to the plant after the incident: everything seems to look fine though it got some wrinkles.

plus the wrinkles are on the sides of the left leaf.

Link: http://s1235.photobucket.com/albums/ff436/atata5050/After%20Plant%20Got%20Stepped%20On/?albumview=slideshow

Thanks Again :)

I'm not sure about those whitish lines running along the inside of the leaves. Have they changed at all since you got the plant, or do they feel different to the rest of the leaf? Can they be rubbed off? If the plant was stepped on flat from above and is just a little wrinkled without any stem damage then it'll probably be okay. I shouldn't think there'd be much cell damage.

The pot will be big enough to hold the root system for the next couple of growing seasons, though it could use some insulation to stop it drying out so quickly. The fine roots grow quickly in response to rain and also die off quickly once the soil dries too much, so a slow-drying (but airy!) pot means more time spent in the roots' comfort zone. Insulate the pot by putting the plant pot in a larger one (say about 1cm gap all round) and filling the gap between the two with sand or something similar. Have the pot tops level, and use a bit of kitchen towel to keep the contents of the two pots separate. If you do end up overwatering, pull out the inner pot and it'll dry off faster.

For the soil, there are plenty of options. Just not many that are economical for a single two-inch pot. Turface is a very good material if you can find any, and you only need a handful. It needs a bit of preparation to get the particles the right size (1-3mm). Grit is good, as long as it's the right size (1-3mm again). A tiny bit of dirt (good topsoil, good compost. Stay away from anything with peat or bark, sometimes called 'forest products') will provide enough nutrients for the plant.

When I say 'tiny' I mean 'not enough to even cover the rest of the ingredients'. Lithops recycle their leaves, so their only major energy drains over the year are roots and a flower. And they'll skip the flower if they're not happy.

By the way, the exact kind of plant you have is Lithops karasmontana 'lateritia'. It's a form found naturally and multiplied in cultivation because it looks nice. The karasmontana and lesliei species have a lot of variation, and most Lithops found on the shelf will be one of those two.

Don't worry too much if you kill this one, so long as you were paying attention to what the plant was doing. Lithops tend to die suddenly when they go, so it's easy to narrow down what went wrong. Usually they turn to mush, although sometimes they just don't wake up after winter if they ran out of resources. Sometimes if they get fried the inner leaves just about survive and emerge from their crispy casing as normal, but not having any old leaves to consume means they'll need a little extra care until they've been through one full growinng season as normal plants.

Once the plant's been through two growing seasons it can be put in a bigger pot. One, the pot will probably be rather cramped by then. Two, you'll be able to control the water supply better and will be more sensitive to the amount of water the plant needs. Lithops will drink whatever water you give them even if it makes them pop, and the more water the pot holds, the less forgiving it is of overwatering.

Don't water on a schedule, it'll mess you up once the plant's repotted and the conditions around the roots change.

Here is a link that might be useful: A useful Lithops blog, with troubleshooting