Pc is now a potato 🥔

Okay, so I was playing F.N.V. and it crashed, I had to hard reset my pc (pressing the power button until it shuts down). Now my pc is running like a potato, it takes ages to shut down/restart, the taskbar won't show, the stuff on my desktop sometimes appears, when I try to search in my files it won't open anything and the start button just won't show up and trigger when I press it from my keyboard. HELP.

P.s. Okay so I manged to search a little and I don't know why it is using between 0%-1% my SSD (Disk 0 C:) and 100% of my external hard drive (Disk 1 D:).