WP Admin Not Working in WordPress! What Should I Do?

I recently set up a new WordPress website for my small business, but I'm running into a major issue with the admin area.

When I try to log in to the WordPress admin dashboard, I keep getting an error message that says "Oops, that went wrong!" or sometimes "Sorry, you are not allowed to access this page." This is making it impossible for me to manage my website, make updates, or publish new content.

I've triple-checked my login credentials and they are correct. I also tried resetting my password, but that didn't fix the problem. I even attempted to log in from a different browser and device, but I'm still getting the same errors. If anyone has experienced this issue before and knows how to resolve it, I would be so grateful for your help!