Probably about now.
I've been stuck on a restore point a couple of times and did a power shutdown where I ended up with just a black screen and a big white arrow.
The first time it happened it would only boot up with a Kaspersky Rescue Disk which took about 9hrs to scan my system.
When it had completed, I hit the restart and went to make a cup of coffee - just to return to find it was running a chkdsk which fixed it.
The second time was just recently when it restarted following restoring with a system image, it just black screened with the big white arrow and had to take it in for repair where they needed to change the North Bridge chip.
I think there was a problem with the external HDD I was using which I've since had replaced under warranty.
You haven't said which version of Windows you are using.
Sometimes you can get it to boot up with a system repair disk where you can select the command prompt to run a chkdsk /f or /r but you also haven't said why you needed to run Windows Repair and I'm loathe to suggest you power shutdown, but if your HDD is failing or failed, you won't have a great deal of choice.