How to Mark a partition ACTIVE from dos?

[John NH]

windows 7 was working properly but now has an error MRB Missing. I used the original disk to attempt repair of MRB but have failed.

I am pretty sure hat I marked a new partition that I created as "active" or "primary"

I am now in dos and can see in DISKPART DIR a  command which says ACTIVE. Is there a way to check which partion is active? And what is the remedy if his is the problem?

[jason2074]

Additional options or steps here - > http://support.microsoft.com/kb/927392