Wontanamo,
Suppose you have a block of data in A2:J15.
In cell L1, enter -2
In cell M1, enter =L1-2 and copy over to U1.
In M2, enter =OFFSET(L2,0,L$1,1,1) and copy through the range L2:U15.
L2:U15 should contain the "mirror" of the data in A2:J15. You can then copy and paste values over your old data.
Could also be used to flip top to bottom. Hope this helps
Alriemer