A lot of those types have a belt underneath that goes from the crankshaft under the deck, but above the blade, and it runs to a gear box in the rear of the deck. Or, the front, if a front drive type. This cable can break, or become detached, or move from its correct position, which will result in a no move condition. Also, look for an idler pulley that will move to tighten up the belt to the wheel driving mechanism. Inspect the control cable for a break in the plastic housing of the control cable. If you find such a break, you will need a new cable.
I have seen a broken gear in a few, but worn parts or broken cable is most likely. RJ

Go to the website below. One of those numbers should get you a picture. Also, the last one is a Craftsman. Go to Sears parts.com

http://www.milacalawn.com/parts.asp

Mod. 125458B000 1B105B21167

Mower model 116-070A302
Ser. 1B286K10071

Mod. 11B 084C062 Ser. 1F 181K12046

Mod. 125458B000 Ser. 1B105B21465

Mod. 917.387230 Ser. 042698M Sears