Thanks everyone for your help, whilst I was waiting for another cmos battery to come I took the hard drive out and put it in an external reader and managed to get my desktop to recognise it (eventually). It was corrupt but managed to run scndsk and scannow on it and am happy to say it is all working well again. 😀
That's good news.. but now's the time to check your disk and be sure: E.g.
HD Tune v2.55
Download HD Tune 2.55
Health and Error scans
Crystal Diskinfo (both free).
At this point you actually don't know the condition of your disk.
Now I would suggest two approaches to help avoid this and give you a recovery option:
a. Run e.g. Crystal Diskinfo either permanently with alerts configured (so when your drive starts to degrade you are alerted) or at least periodically.
b. Use disk imaging routinely and regularly e.g. Macrium Reflect (free-paid) + large enougn external storage for image file.s
The very act of disk imaging (all partitions comprising Windows and any others as you like) checks the intergrity (CRC check) of the data on those disks.
Note these checks are all different in their significance.
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