Mario -- If you have a newly installed Operating System, you will have to reinstall TRS and any SP's, of course.
The big question is whether you have a backup copy of the Local folder from sometime before the crash. If you do, you can just copy it over the Local folder in the new istallation, delete Assets.tdx, and let TRS rebuild the latter. After that you will have everything back in place that was in your system at the time the Local folder was backed up.
If you don't have a backup, is there any chance that you can put your old hard drive in an external case and find the Local folder from your previous installation?
Otherwise, I agree with Quiebus -- well, whether you have to download everything again depends on your storage philosophy. If your old hard drive was partitioned, and if your downloads were saved in a partition other than the C:-drive, then its likely that your downloads can be gotten off the old hard drive.
Dick