Please advise,

Have a Sears lawn tractor, 19.5 HP briggs & stratton (model name I/C
Platinum). Anyway it just grinds when the key is turned to start. This
problem happened once yesterday and then my wife got it started, and now
it will not start. If it was a car I would be looking for a starter. I
have no experience with small engines other than cleaning carb, fuel
filter replacement, oil and filter replacement.

Thanks very much for any help.

Jerry S.