If I recall, in rom monitor type
o/r 0x2102
i (initialize)
This should reintialize the router to boot from NVRAM.
Once it's booted you have to go into global config and change the register to 0x2102 and save it to make it permanent.
Router#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#config
Router(config)#config-register 0x2102
Router(config)#end
you should then do a "show ver" and you should see that your register is 0x2142 (0x2102 after next reload).
SpudNuts(ITC), USN(Ret), CCNA, BSCI, BCRAN, CST