Hello, friend.
Sorry to know you're having a problem with your Mac. We're users just like you and we're here to help.
The advice given above by den.thed is sound. EtreCheck will run a diagnostic and allow us to know what's going on inside your machine so that we can give you the best help that we can. It will show us no private information.
You can find EtreCheck in the Mac App Store. It's a small download... and it's free... and it's no advertisement. It's a tool that was developed by another user here in the Support Community for just this sort of problem.
We can help you, but we need your help, too.
Thank you. :)
edit - EtreCheck will also tell us exactly what Macintosh model you are having trouble with.