There are ways how to achieve that... hoping that your data is not on missed tape. But this method might take you down the longer path than to wait for tape to come back (unless is lost).

The missing tape is jammed in damaged tape drive, I have sent this device in a data recovery laboratory.
I don¿t think when, and if, it will come back.
Could you tell me the procedure?

Many Thanks
Marco

As I said, you might not need it in the first run.  You will only know that if you start recover (unless that was head).  To restore is without tape you can check thread where we discussed usage of scanner and uasm programs recently (also explained in scanner manual).