Root [AT&T] Help! Galaxy s3 fubar

[EpicMyst]

I updated CM10 on my AT&T Galaxy S3 to the 4.2.1 version from the 4.1.1 version and it worked fine except I lost all my contacts, so then I found out that I needed to flash Gapps, which I did but then as soon as I booted the phone it wouldn't load and kept telling me all the Gapps stuff has stopped working so then I made it to the settings screen and then reboot into recovery and reflashed the CM10 nightly and now the phone won't boot past the rotating CyanogenMod logo and recovery won't work and nor will download mode. I have no idea what to do and I am going nuts as I need the phone tomorrow. PLEASE HELP.