My MacBook Air is showing question mark folder and not opening. While reinstalling the Mac OS again as per the process it shows where you want to install Mc OS and there is no option available to move forward. Can anyone suggest how to shot out this

I understand your MBA starts up to a folder with flashing question mark icon. Following the instructions in If your Mac starts up to a question mark led you to Reinstall macOS, but the installer can't find a disk on which to install macOS. Is that correct?

Please start up from macOS Recovery again and follow these instructions to erase the startup disk: How to erase a disk for Mac. Assuming you get as far as Step 3, choose Mac OS Extended (Journaled).

After it finishes erasing the disk, quit Disk Utility which returns to the macOS Utilities window. See if you can reinstall macOS again or Restore from a Time Machine backup, however you want to proceed.

If you do not succeed it is possible the startup disk has failed or your Mac is suffering from some other hardware problem. In that case, please contact Apple Support.