The file was managed by an ex-employee and forgot to ask him the password during the transition.
@diskborste, thx for the reply. The sheet contains sensitive data so I am not allowed to distribute it.
What i can tell is an Excel 2010.
Thought you meant Seotools license.
There are various password hacks if you google.
All you can do is crack or bypass the password for Excel 2010,as for restoring it, it is impossible.