It's possible that the driver you are trying to install is not compatible with your device, which is why it is failing to install. You may want to check with Dell's support website to ensure you are using the correct driver for your specific tape drive model.
If you have the Quantum LTO3 driver installed, you can try uninstalling it and then reinstalling it using the correct driver for your tape drive. The correct driver should also include the .inf, .cat, and .sys files.
As for recovering a previous hardware configuration, you can try using System Restore to roll back to a previous date when the tape drive was working. This may restore the missing tape drive device and allow you to install the correct driver. However, be aware that...