3TB Hard disc became "unallocated", how to recover?

[jumanji]

I shall be around.

You may go through screenshots 1, 3 and 5 (post#7) in http://www.sevenforums.com/hardware-devices/310295-lost-partitions.html#post2584426 to familiarise yourself with Bootice. (The later part deals with saving the sectors which does not apply here)