Can you try a "safe boot"?
Reboot and hold down the shift key continuously until login.
If you can get that far, open "users & groups" in system preferences.
Then check the login items for your account.
What's in there...?
By the way, it sure helps if you tell people:
- WHICH Mac you have
- WHAT YEAR it was made
- WHAT VERSION OF THE OS is on it.