While entering purchase bill its wrongly posted to some other Ledgers?

You've come to the right place, @viswanathan.

I can guide you in correcting the bill that was posted to an incorrect account. 

1. Go to the Accounting menu.
2. Select the Chart of Accounts tab.
3. Locate the account where the transaction was recorded.
4. From the Actions column, click View Register.
5. Find the bill. 
6. Select Edit. 
7. Change the posting account, and click Save and close.
8. Hit Yes to confirm.
   

Also, you can generate the Transaction Detail by Account report. From here, you can locate the bill and make the necessary changes on it. You can read through this article for more information about managing your bills: Enter and pay bills.

Keep me posted if you have other questions or concerns about tracking your expense transactions. I'm here to help.