Can't Change A Standard Account To An Administrator Account

I recently logged onto my account about 2 days ago to finish a project. The music file I used for the account was could not be found and when I went to locate it I was told I didn't have administrator rights. I went to Control Panel because I was sure I was an Administrator, but sure enough, I was set as a Standard User. I tried changing it up but it wouldn't change. I tried changing the account name also, and it wouldn't change. I could only change account picture. I can't open UAC, I click it and it blinks but nothing opens. I deleted any recent program installations,I booted in safe mode, however I was still not able to change my account,I tried activating the hidden administrator account but I received an "access denied" message,I tried creating a new account but I received the following message:"The specified account name is not valid, because account names contain the following characters: /[]":;|<>=+,?*Please type a different name."I didn't use any of those characters in the account name.I ran 2 different virus scans, and they came up with nothing,I turned the computer off, unplugged everything, and pressed the power button for 30 seconds, and rebooted, but still nothing!My roommate shares this computer with me, and her account is still an administrator. However she has traveled and I haven't been able to get hold of her yet. We share music files and the file I was trying to use is in her account.why my account was changed and how I can change it back?