Always make a backup before you flash a new rom or theme. It depends on what recovery image you have, if you have cyanogen then you can perform a nandroid backup, If you have RA-dream 1.5.2, then you have the option for performing backup and restore with (bart) and a nandroid or nandroid+ext 2. Now since you did'nt make a backup then you have to re-flash your rom to get back to your original theme, but before you do that go get the (backup for root users) app so you don't have to reinstall your apps. Once you flash your original rom then reinstall backup for root app from store. Only check the APK box, because if you check all it will screw up your rom. Another thing always wipe before you flash roms or themes because the old data will bump heads with the new data and that will screw things up. When your get everything running return to recovery mode, turn off phone then hold home+power for a couple of seconds after the buzz. Go to console hit enter then type in fix_permissions then then let it do it's thing. Then hit the back button and perform a nandroid backup. Now if you can try out new roms and themes and always go back to your original rom by restoring, but make sure you wipe before you restore just to be safe. It's not as complicated as it seem just follow instructions and your good to go, any time you need help just hit me up. Oh I almost forgot, if you want to make going into recovery simple get quickboot app from market