how to unlock a file when access is denied . . .

i am having a problem opening certain files on my computer and i am always noted by the sign, write to disk, accessed denied. when i researched this term it said it could have something to do with your anti virus locking files. therefore i was wondering how i could stop avast from doing this. i have tried to go through my settings and have also restarted them too, to no avail. any help is welcomed and thanks so much in advance!!

What/which file? ???
Is there any indication that avast is locking your file(s)? ???

I doubt that avast would be locking your files, depending on what files they are you may need Admin permissions.