ntldr missing for windows pro installation

a system had a virus(ralia odinga) for like 3weeks, on detecting I tried removing virus could not,tried formatting could not,tried formatting from DOS could not,then I now slaved it to another system then formatted from DOS,after that I tried mounting a new O.S but it tells me NTLDR missing, please what can I do my email is olamidethomas2001@yahoo.com