OK, did you make a backup from recovery (a "nandroid" backup)? If so, just restore that.
If not, do you know what you did when in recovery?
If you flashed a ROM without doing a wipe first, you could either go back into recovery and do the wipe now, or maybe try reflashing the Android Revolution ROM without a wipe - if you didn't back up your data first then reinstalling Android HD might let you boot the phone and take a backup now.
Ah, seen your edit.
Did you leave the ROM .zip on the phone? If so it doesn't matter whether the computer can see it or not: boot into recovery and install it from the phone.
If you didn't leave the zip on the phone, the question is how to get it onto the phone when you can only boot into recovery. In the old days you'd just go into recovery and mount storage over usb, but I doubt that any recovery does that now (not had mine long, so not sure of all of the details yet). If you have a USB OTG cable you can just copy the ROM zip to a usb flash drive, then connect that to the phone and install from recovery from the usb drive. If you don't have a USB OTG cable, it's well worth getting one!
This is fixable, it's just a question of whether it can be done quickly and without data loss (is that a problem, or do you have backups?).