I'd look for a reason that the 100A fuse blew.. or the new one may blow likewise.
Think I would rig up a light bulb to plug in to the fuse slot. If the lightbulb glows, then there is a short. Find the short before plugging in a new main fuse..
I replaced the 100 Amp fuse in the fuseable link and that solved my problem. Tractor now cranks and all lights work. Thanks so much to all of you who gave me advise and help.