I accidentally (new to quick books) hit reconcile discrepancy and it reconciled the entire month. How can I undo this?

Hi office-karunia-c,

Welcome to Community and thank you for choosing QuickBooks Online.  I can relate to your experience when navigating through the reconciliation process and accidentally pushing a button unexpectedly.  QuickBooks Online also understands this and has a feature that allows accountants to make the necessary corrections to get you back on track and in the right direction.  In this situation, I recommend reaching out to your accountant to take care of this for you.  If you don't have an accountant we can assist you with locating one in your local area.  

For future reference, here's an article to guide you with removing individual transactions from reconciliations when you've reconciled them by mistake.

I hope you find this to be helpful.  Let us know if you have any other questions.  We're here for you!