HOW TO GET WINDOWS 11 BACKGROUND BACK AFTER CORRUPTING THE COMPUTER GUIDE, NO GLUE NO BORAX?

HEY, HELP ME BECAUSE I MESSED UP DOWNLOADING THE UNOFFICIAL HOMESTUCK COLLECTION AND IT SEEMS SOMETHING I DELETED TO GET SPACE TO DOWNLOAD IT CORRUPTED SOMETHING IN MY COMPUTER! I WOULD SEND PROOF THAT THE BACKGROUND IS MISSING BUT I DONT KNOW HOW TO ADD THE PHOTO!

PLEASE HELP!