How to get access to the file which was recovered from backup but was originally protected with password?

The disk was backed up with Acronis TrueImage 2017 (sector by sector backup). One of the .odt files was password protected before backup was done. After retrieving the file from backup it become inaccessible and the following message is displayed: “You don’t have permission to open this file. Contact the owner or an administrator to obtain permission”. Granting permissions for other files under Windows works but for this particular file there is no change - it remains not accessible. Its icon shows a padlock.
There is no window allowing for giving password which is known.
Could you please help me with accessing this file?
Thank you.

What software did you use for password protection? What OS? Was it NTFS encryption? Or BitLocker? (If unsure, at least write which steps did you follow to set the protection.)
Because what you describe doesn’t sound to me as LibreOffice encryption, and as such, it should be removed (if possible at all) using the same software.

google password open office for sites which allow passwords to be cracked.

Thank you for your interest in solving my problem.
The .odt document was saved using regular OpenOffice Writer menu driven commands (under Windows 10): Save As, then the option “Save with password” was marked. No special software was used for encryption. Neither NTFS encryption nor BitLocker were used.
The problem is with accessing the file and not encryption itself (I know the password).
For some reason I can not grant the necessary permissions to the password protected file. Granting permissions for unproteced files works well.

This looks like a Windows file protection problem. Look at the file Properties > Security > Advanced - is your account the file Owner? If not take ownership of it - you will need to be using an account with administrator privileges.

If you do own the file you could try starting LO with “Run as administrator”. This sometimes such problems.