Renaming duplicate column names

Quote from SUBHASHn

It is stopped near 2090 cell...in total I have 65k cells in the A column

What stopped? Did the macro finish running?

Can't tell the players without a scorecard... As Mumps said earlier, post your workbook and code.

I ran the code on a test file of over 600K rows and 1 column. No problems. Run time was less than 3 seconds.