can't use 3tb hard drive

after installing windows 7 home premium from ultimate,my 3tb seagate barracuda doesn't show up on "my computer".
i can see it in disk management though,but there are 2 partitions of 2tb and 700gb.
since i have files in it,how can i use it again without having to format the drive ?

Formatting the partitions will seem to do nothing because they aren't mounted.
To mount a partition using Disk Management: Right-click on the partition's name, click "Change Drive Letter and Paths...", click "Add...", choose a mount point, and click OK.