Thank you for visiting the Community space, deepthi.
I'd to verify some details if you don't mind. Is there an error message when you try to log in to link you bank in QuickBooks Online? If there's none, you'll want to check following scenarios why you're unable connect your bank account:
The bank may not be a participating bank.
Your bank might not connect to all types of accounts (for example, personal accounts vs. business accounts).
Bank is having a system maintenance.
Some banks have multiple names on our list. You might want to check and select the correct one, or try all possible bank URL.
Then, reach out to your bank and check for any maintenance update or request to establish a connection with QuickBooks. If everything is good from your bank's end, please make sure to select the correct bank name when connecting the account.
Here's how:
Go to the Banking or Transactions on the left panel.
Select Link account or Add account.
In the Connect your bank or credit card to bring in your transactions field, enter the URL listed for your bank.
Follow the on-screen instruction to connect your account.