Possibly Erased Flash: "device does not contain a valid magic number"

[Garagedays]

I got a Cisco Router 2621 and needed to blow out the passwords.  I followed a youtube video that helped but every time I restarted the router none of my changes saved so I tried to save the configuration and I believe it was going to erase the flash memory, I said yes.  I thought I was good to go until I restarted the router a few days later and now I am stuck in rommon mode.  It tells me "device does not contain a valid magic number".  So it appears to me I need to reload the software.  Any help would be appreciated in guiding me to fix this router via a method I am not aware of or reload software on the router which I am new to.  I have been training for ICND1 and I just got to the point I need to start practicing on a device.

[Ben Walters]

First you can check is Flash really was erased by issuing the dir flash: command, if you don't see the IOS image file you will have to load it. If it is there you can just use the boot <image name> command.

If you need to load an image back on there you can either do this using xmodem, which takes forever to load a file, or TFTP.

Here is an xmodem guide, you will have to get a terminal program that can transfer files, Putty can't, I usually use teraterm.

https://www.cisco.com/c/en/us/support/docs/routers/2600-series-multiservice-platforms/15085-xmodem-generic.html

Here is a tftp guide, solarwinds has a free tftp server program is you need one.  

https://www.cisco.com/c/en/us/support/docs/routers/2600-series-multiservice-platforms/12714-76.html

Also when you were in the loop where it didn't save your config after you blanked the passwords you probably didn't set the configuration register back to normal so when it booted it would bypass the startup config.

Hopefully this helps you get this router working again.

[Garagedays]

If it is gone, what is the best method to get the image I need to load?  And what image should I load?

[Ben Walters]

If you have another router of the same type I would just grab a copy of the IOS from that, it seems that these routers were end of life back in 2012 so it will be very hard if not impossible to find an IOS image for them.