Is repentance permissible for having extracted a fingerprint by commissioning someone when it is not possible to go back and extract it oneself, and is the salary resulting from it lawful or unlawful?

If the work is permissible and you observe the Sharia guidelines in dress and speech, then there is no harm in it or in the salary. As for forging the required document, seek Allah's forgiveness for it and do not return to it.