I accidentally removed all the permissions from a file. Now I don't have permission to chmod it. Is there any way of chmod(ing) the file back?
I suspect there's more going on than your question states, because that shouldn't happen:
As you can see, having no access to the file is no bar to changing the mode back. Could you tell us more about what you did, what you see, and what's going wrong?
In situation if you are not a owner of this file you can`t change mod of this file.
In this case try to use chown command from root user: