I take it that means you hadn't installed a custom ROM either?
So had you made any app/data backups (e.g. Titanium Backup)? If you have, then you can install whatever ROM you like, then restore those data afterwards. Read the rooting guide and faq in the "all about rooting" sticky post (red link in my sig) for instructions. The "How do I flash a custom ROM?" section of the FAQ includes the link
XDA Developers - Desire Index, which is the best place to find a ROM.
However, what if you haven't made a backup, or haven't recently? Installing most ROMs requires a factory reset (because the settings generally aren't compatible, so they won't boot otherwise), but that erases your data, so if you haven't made a backup you probably don't want to do that. Now you may have no choice - there are no promises here. But if you don't have adequate backups, there's one option that might work: flash a ROM that is compatible with your original software. If you can get it to boot, you can install backup apps (such as Titanium), back up your data, take a nandroid, then it's up to you after that.
So, do you know what software your phone was running? If not, at least the android version? From your radio version I reckon your phone is GSM (i.e. you have a SIM card), and I assume you were running Froyo, in which case you could try flashing one of
teppic74's ROMs. These are rooted, stock Froyo, so very close to the original software (without any network branding). Pick the one closest to your software version (if you know it), but one that does not include a radio (don't want to flash a radio right now). Copy to your SD card (with a card reader, or boot into recovery, connect the phone to a computer, and use the mount/storage menu in recovery to mount the card on USB then copy the file). Then select "install zip from sd" from the recovery menu, select the file and install it. Do not wipe the phone first.
Now let's be clear: I cannot guarantee this will work. I'm assuming you are running rooted stock software on a GSM phone, and hence hoping that this ROM is close enough that you can flash it without wiping. I'm also assuming that you are not using a2sd with an ext partition (because most people install that as part of a custom ROM, which I don't think you've done). So a lot of assumptions here, and if any of these do not match your actual situation then please don't proceed, but let us know what your actual setup was. But if you have just rooted (and S-Offed!) and not installed a ROM then I think there's a reasonable chance this will work - teppic's ROM was the first I ever flashed, and I did it without a wipe, so it is possible.
