C9200L Switch Recover from a Corrupt or Missing Image
The Supervisor boots into Rommon mode if the image specified is corrupt or no image file exists. Typically, you should have more than one image in the bootflash: device so that the switch can be recovered.
Complete these steps, in the order given, to facilitate a successful image recovery from Rommon mode without any valid image.
Make a console connection to switch with COM1 with these settings:
9600 bps
Eight data bits
No parity
One stop bit
Press Enter. If you get the Switch: prompt, If the switch continuously reboots, press Control-C to prevent autoboot and to get into Rommon mode
Verify that there is a valid file present in the bootflash: by issuing the dir bootflash: command, as this example shows. If you do have any valid file,. Otherwise, continue to the next step.

Ignore the startup configuration with the following command:

Boot the switch with the packages.conf file from flash.if a valid file present in the bootflash

Connect the management port on the switch to laptop/window machine to access a TFTP server.




The system image has been copied. Issue the dir bootflash: command to note the file in the bootflash:
Set boot path to flash:

Enter the verify command to verify the integrity of the downloaded file. If the verification fails, you have to download the file again.

Follow more instruction from cisco website:-
https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst9400/software/release/16-9/configuration_guide/sys_mgmt/b_169_sys_mgmt_9400_cg/recover_from_corrupt_or_missing_file_image_or_in_rommon_mode.pdf