Car is in limp mode,but everything else seems fine now,how do I fix this problem & clear the code ?

Question

Started to install battery & didn't notice the terminals were reversed until the cable touched the post & sparked. Hooked battery up correctly & started car,guage needles jumped all over & it said FUSE on the odometer (radio & door locks not working). Found burnt 20 amp fuse under yellow shield in fuse box under hood & replaced it & everything appears to be working properly,but when I drove the car it was in limp mode & has code p0700 (1st gear only). I don't have any diagnostic tools & don't know much about working on cars obviously,although I was a Journeyman Partsman 30 years ago & then the mechanics wrenched on my rides. I know that there is nothing physically wrong with the transmission & am looking for the cheapest remedy possible. It's Christmas time,I'm broke & am hoping that Santa will bring me a solution to my problem. Any assistance would be greatly appreciated as driving at 25 miles per hour is ruining our holiday season. Thanks & may your Christmas be a merry one !