"Can't open" could mean lots of things, so please add more. It could mean
- I have no idea how to do this
- I know how this should work but something is missing on screen (what?)
- When I try I get an error message (what?)
- When I try something weird opens instead (what?)
- When I try nothing at all happens
- something else?
Just remember: we can't look over your shoulder and there are countless different problems.