You have a chance to get some of the information back to recreate the scripts. If the following files are readable, then you may be able to get them back.
Default.xls (in the main test folder) is the datatable. If this file is not corrupted, you should be able to open it in Excel and recover the data. I would not copy this file to the new test. It would be better to copy the data, that way you're not introducing possible corruption to a new test.
Some of the other files in the main folder may be able to be opened by a text editor such as Notepad, but you don't really need them to recover the script.
In the Action# folders, you'll find the Script.mts. You should be able to get the VBScript of the actions from these files.
The Object Repository is in ObjectRepository.bdb and it's possible to copy it into a new test, but it is more likely that you'll have to recreate the object repository.
For a full list of test files and what they are, check out HP's document KM181680.