Hey there, win 8.1 allows you to reset your pc without a disc. GO to pc settings and down at the very bottom is a reset option. Or do a search and type in factory reset. If you want to do a total clean install and lose files and/or folders, do a recovery. Preferably from a system image that should already be in the options for recovery.
If that makes sense.
I found out how to repair my pc by floating around in it and peeking at the instructions and outs of it.
My advice? ...get to know your pc hun, inside and out. Will save you many bucks if you do.
Hope I helped a little.