Hard drive partitions missing

[psm360]

I had 3 partitions on my laptop HDD of 250 GB.
C = 35 GB, D = 100 GB, E = 98 GB
yesterday i found D drive missing from my computer, only showing C & E
now today i found my E drive also missing and in My computer only C drive is visible, there are no traces of other two drives.
what is the reason of this & how it can be recovered.
I tried EaseUS Data Recovery Wizard & it showed my other drives but they were marked '*' and not named D or E drives.
please help me.

 

[rolli59]

Do they show up in disk management? Right click my computer, manage/ Storage/disk management.

 

[psm360]

in disk management on top block only 2 are being shown, C drive & system reserved
in disk 0 section it is showing all four partions, the above two plus space of missing partitions
http://imageshack.us/photo/my-images/834/diskmanagement.jpg/

 

[rolli59]

They are both there and have lost their allocation that is drive letters! Assign them again.

 

[psm360]

how to do that?

 

[psm360]

an error is coming when assigning drive letters
see the link
http://imageshack.us/photo/my-images/338/diskmanagementerror.png/

 

[rolli59]

Looks like you have a corrupt windows installation or a failing drive. Try doing repair install of windows.

 

[psm360]

Everything repaired.
Firstly I backed up & recovered all data from missing partitions with the help of Easeus recovery wizard. then ran windows setup. I setup it showed only C drive, then i formatted it & deleted the partition. Total HDD size was only 35 GB. Then restarted windows setup, then it showed one missing partition (D). Then I formatted this partition and deleted it, So unallocated size became 135 GB. Then I again repeated the above step & finally E drive also came. then formatted it deleted it, to till then I got the full storage of my 250 GB HDD, After that I partitioned again , installed windows. Now its working fine.
But till now I couldn't find the reason behind all the mis-happening.