Windows 8.1 booting issues after removing partition

So backstory time. I built a desktop and threw in my laptop HDD and installed the proper drivers, and everything was perfect. Then I decided I should probs get rid of my Music partition and instead integrate it into my main Windows one (not even sure why I made a separate partition). So I went into another Windows install on a separate HDD and copied over my music to transfer back to my HDD, since I don't have enough space on it. Then here's what seems to have messed it up: I deleted the Music partion (which was to the left of Windows) and extended the laptop Windows HDD inside a different Windows drive. Now when I try and boot with either System Reserved or Windows as active, it takes 5-10 minutes on "Preparing Windows" after I sign in, it just boots to black desktop with a mouse. ctrl+alt+delete pops up right, but task manager doesn't open; ctrl+L also locks the PC. It has the same results with Safe Mode with Networking enabled. /ScanOS shows no Windows OSes. I have no restore points made, so I gotta figure out what to do. I have 8.1 Pro that I will upgrade to as soon as Windows works again, as the OEM code from the laptop doesn't work on the desktop. Honestly, if you can tell me a way to keep my programs and Appdata working fine on a fresh Pro install, it'll work perfectly.