if you can boot then make a full backup and then restore from backup if it goes wrong, it is honestly not worth the risk. There are a couple of ways that you could get yourself into the position you are in, and without more detail, you'll be struggling. Explain precisely how you ended up where you are now, leave nothing out, and we might be able to help. I've been in similar positions and been sweating for many many hours to get it to work.
First of all you must of installed windows, in raid mode.
So changing it to Sata will stop it from booting as a raid 0 array is striped over two hard drives minimum.
That is why it does not boot.
If you make the drive as part of the raid array windows will boot again.
And no it does not wipe the data at all. Unless you set a new raid array up on the two drives then it will format them. Just add the drive to the raid array again.
supposedly a RAID was installed and configured with windows 7. the raid became "degraded" but the computer still booted. then it just went to the black screen of death with a blinking prompt. took it back to the guy who built the computer. he was able to boot it at the store. I was able to boot it at home, but then, "Black Screen of Death" again---just the prompt. now no boot, no joy.
add another disk and in bios rebuild the array, not a new array, but a rebuild and you might be ok, if this does not work you are out of luck. so if you can get it 'working' making a backup first would be great.