Is there a bootable image on the device's flash memory? if so you can tell it to boot that while at the rommon prompt on console. If not, you will have to first put a bootable image onto flash or other accessible location.
With a 2960S, the easiest recovery is to use a USB memory stick plugged into the switch's USB Type A port directly as the boot device. See this thread for some tips on that. The documentation says up to 1 GB memory stick is OK but folks have reported success with larger - you must format it FAT 16 though.