Nothing special should be needed. Drives are recognised automatically by Windows if they are recognised by the BIOS, partitioned and formatted. The one possible exception might be that these 2 drives are SATA drives while your restored OS is an old version of Windows XP that doesn't read SATA drives or drives bigger than 127 GB.
As you don't tell:
- what the BIOS says
- what disk management says
- what GPARTED (free download) says
about these disks it's impossible to tell anything sensible about the cause in your case.
Let's hope you have a current backup of those 2.5 TB of important stuff. As we say here: if the owner doesn't make a backup of some data he doesn't find it important.
Kees
My hard drive which had windows on it recently died on me. So I installed it again to a clean drive. But what i can't figure out is how to get my other 2 hard drives to be recognized on this new system. I don't want to lose any of the data.These other 2 hard drive have about 2.5 tb of important stuff that I need

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