help!

after my c/ drive/ssd crashed and destroyed my win10 install, i used another drive to install win8 and then put my previous win10 music/ap backup drive E in the system to copy over files to the new win 8 install. i couldn't access anything, had to spend time giving permissions (wtf) for everything (using admin account). now some files are appearing zipped (they were not previously), and i am asked for a password to 'unzip' them...what the heck is going on? there was no pass on anything. took ownership of the drive/files/items in files,still pass protected...any help would be neat, as i can't afford win10 install media atm (had taken advantage of the free upgrade last year)...and my mouse is not able to scroll window windows (browser windows, yes, just not os ones)...

Welcome to the forum. First off remove the backup drive it sound like you are infected with ransom ware if so it will encrypt all your files even on local network. Unless you want 8 not 10 download the iso for a clean install of 10 from Microsoft
You dont need a key it will active once on line as its registered on ms servers so you dont have to pay.

Try uploading one of the zipped files to VirusTotal - Free Online Virus, Malware and URL Scanner it will check if it contains any virus if may not show if its just encrypted but a lot do that and when you open them it infects you again.
Run Malwarebytes Anti-Ransomware Download see if it picks anything up if it is ransom ware you need to know what it is some files can be restored depending on whats done it.

It sounds like new CryptoHost Decrypted: Locks files in a password protected RAR File ransomware Bart Ransomware Locks Files in Password-protected ZIP Files - Security News - Trend Micro USA