Can I get a report of bank reconciliation after I have undone it? Does the bank register shows the same transaction Cleared after undoing bank reconciliation as before ?

QuickBooks Online (QBO) generates a report after you finish a reconciliation, @Swapna Tiwari.

Please be advised, this is a static type of report. Any changes you do to the reconciliation period in question won't reflect on the report. What you can do is open the Audit log to see these changes.

Here's how:

1. Go to the Gear icon.
2. Select Audit log.
3. Tap the Filter menu.
4. Under Events, choose Reconciliations.
5. Hit Apply.

Check out this article for additional information: How to view details for missing reconciliation reports or reconciled transactions. 

As for what happens on the transactions when you undo their reconciliation status, those that were downloaded will go back to Cleared. While those transactions recorded by hand will go back to blank.

I'll share this article with you as well: How do I view, print, or export a reconciliation report? In case you need to get a hold of reconciliation reports, it has the steps on how you can locate the report, along with the steps to print it. You can also find the steps on how you can transfer this report to Excel.

Tag me in a comment below if you have other questions about reconciliation reports in QBO. I'll be around to help you out. Enjoy your day!