I'm delighted to have you here in the Community today, @sales264.As I check here on my end, QuickBooks Online (QBO) can be accessed via desktop. Let me assist you in isolating this so you can access your QBO account via the website.
If you're on your desktop, try accessing your account through an incognito window to rule out the possibility of a webpage issue. Use these shortcut keys to open an incognito window in any supported browser:
Chrome: Ctrl+Shift+N
Firefox: Ctrl+Shift+P
Safari: Command+Shift+N
Once done, proceed to open QuickBooks Online in your browser. If it works, clear your browser's cache. This way, you can use QuickBooks with a clean slate. You can also try accessing QBO via other compatible browser.
In case you're using the mobile version of QuickBooks Online, I recommend resetting the app data. Resetting the app data plays the same role as clearing the cache from your web browser. To begin, here's how:
iOS
Go to Menu ☰ and tap Help & Feedback.
Tap Refresh Data.
Note: A message appears “Caution. If there was a problem getting your latest QuickBooks Online data, you can refresh it now. It may take a few minutes.”
Tap Refresh to confirm.
Android
Go to Menu ☰ then tap More Options ⋮.
Tap Settings then Refresh Data.
Tap YES to confirm.
I've also got you these articles for future reference: