Well, you might have an alternator problem, but before you do anything rash, check very carefully for a fuse being blown. I'm not referring to the main fuse you would normally think of, it would be an additional fuse besides that one. I can't remember all the details but a couple of years ago there was a discussion on here about a fuse featured on some Deeres that would affect charging but nothing else. Maybe some of the Deere folks can help out here on that. What engine is in your L120?

It's a Briggs 20 HP Twin OHV and right after I posted original it dawned on me we are talking magneto and not gernerator. I'll take cover off tomorrow and trace the wiring. I can't imagine magneto problem and a fuse seems to be the answer but I would think that would be outside the motor cover. I've got an acre and a 1/2 with a wedding rehearsle dinner coming up in 2 weeks and if I don't get grass cut soon, I'll be in big trouble. Thanks Mownie

How about some specific model and type numbers from the engine? "Briggs 20 HP Twin OHV" is still too vague and you can't get to a Briggs site manual without Model & type numbers.
Magneto??? Generator??? Your engine has both, and each serves a different goal.
Magneto creates the spark for the spark plug ignition.
Generator (alternator) provides electrical power for keeping the battery recharged and to address the 12 volt loads of the electric PTO and lights.
Magneto problems will not affect the PTO or the operation of the starter. Generator problems will not affect spark.
Generator problems certainly will have an influence on whether the PTO works, and whether the battery stays charged to crank the engine.
When we get the model & type numbers from you we will be able to look at the IPL and see if your engine has a fuel solenoid. The reason for "need to know" on that is because a Briggs engine that does not have a fuel solenoid will happily continue to run after the fuse you're thinking of blows. In that case, the PTO would quit but the engine would run on. But the next time you tried to start the engine, the blown fuse would prevent the starter from working.
IF....the engine DOES have a fuel solenoid, the engine would have died the moment the fuse blew.
In fact, the engine dying would probably have been at the top of the complaint because you would have failed to note that the PTO quit.
Looking like a problem in the charging system, or a blown fuse to me. But remember, a fuse does not blow without a reason.

model 406777; Type 0139 E1; Code 040203VG
Now that G at the end of the code could possibly be a C but it appears to be more of a G with light impression of the stamping. I sure apreciate your help here.

OK, IPL reveals engine has a fuel solenoid. This implies that you did not have a blown main fuse (or else the engine would have died).
Before you go any further with suspicions, make sure the battery actually is in a state of full charge. A fully charged battery should show over 12 volts using a volt meter.
The fact that the PTO stopped turning, and now the starter will not make a sound, leads me to suspect that the PTO switch itself has a problem, or has become unplugged from the wiring harness.
PTO switches are usually configured to prevent the starter from engaging if the PTO switch is left on because the PTO clutch would be sucking up battery power needed for the starter AND the extra drag of the deck would also make it hard to turn. So the 2 simultaneous problems would make me look first for a problem with how the PTO switch connects to the tractor wiring. If all looks OK there, I would test the PTO switch for proper continuity according to the tractor wiring diagram.

Thanks Mownie. I copied this info and put in my manuel for future reference. What is IPL? I unpluged and clean all wiring connectors with alcohol and shop rags this morning. I plugged everything back together again and was able to cut all my property in about 3 hours without any problem at all. When I was finished I restarted motor and it started right back up as fully charged. Had to be lose or oily connection. I didn't do anything to PTO switch. I apreciate your help in this matter. I really didn't want it to spend time in repairshop and they may not had found the problem or in this case, a loose connection.

IPL = Illustrated Parts List. That is where you can view the Briggs part numbers for your engine.
Click the link and plug in your numbers per the instructions on the page. Example: in your case you put in 406777-0139-E1 exactly like that, then press GO. When the offerings appear, select IPL English.

I hope it was just a one time problem that you solved by cleaning and securing all the wire connections. I'll keep my fingers crossed.
If it surfaces again, get back to this same thread to pick up the trail, that way all the info is still in one place.
Good luck.

Here is a link that might be useful: Briggs webpage for IPL

Well, I'll be dipped. Thanks a million. I believe it was a loose connection preventing a charge to the battery. The battery would get so low it wouldn't let me go in reverse with mower engaged or enough charge to keep PTO switch engaged and sometimes, just die. Depending on which one came first. It's just what it seems to be right now. Not an exact science in my garage by any stretch of imagination. Thanks for supplying the logic Mownie. If I have any more problems with it, I'll be back.

OK! We're here if you have more trouble :^)