You can use a Bootblock manager to write this bootblock back to a disk. Just search for 'bootblock' on www.aminet.net
Warning: If you don't use a Virus-Killer, like VirusChecker, your disk with the bootblock will infect other disk's or your system with a virus if the bootblock contain's a virus.
Only if you use softreset on a real Amiga or reset on WinUAE. Have never tried it on WinUAE.