Start up issues and desperate for help.

I have a refurbished Latitude E6520.  W microsoft windows 10 pro w product key

Automatic repair couldn't fix. Says Log file: C:/Windows/System32/Logfiles/Srt/SrtTrail.txt

I tried using command prompt  and it says you need to sign in as administrator but there arent any

Same message for system image recovery and system restore. 

I need it for work asap

I don't care if I loose any files on computer as long as it works