If I understand your story correctly, it seems that your problems started after this step:
daebis wrote:Today i changed the hdd compartments.
What exactly do you mean by "hdd compartments"? It might help if you attach a photo (e.g. 1024x768 - it doesn't need to be full-size 16MP

) to your reply, showing what you mean.
What change did you make, exactly? (From what, to what?)
Which hard disks(s) did you handle / touch in any way?
Why did you make this change - what were you trying to achieve?
daebis wrote:On entering BIOS None of the hard disks are being detected.
But when i disconnect the 2 TB hdd, the computer works perfectly fine.
Just to clarify - do you also mean that with the 2TB disk disconnected, the other 2 disks are then reported correctly in the BIOS setup screen? But with the 2TB disk connected, the other disks are not shown at all in the BIOS setup?
daebis wrote:atleast one of the partitions out of the three should be recognised???.
No, not necessarily. There are many types of disk failure, which prevent host access to all parts of the disk (i.e. all partitions). The disk drive itself has no concept of partitions.