Hopefully by now you've caught that your use of "lastrow" in your
cells reference is transposed.
It's supposed to be cells(row,column)
you're using cells(20,lastROW) which is backward.
These two are equivalent:
Range("B2:T" & lastrow).Select
Range(Cells(2,2),Cells(lastrow,20)).Select

I know, when using column LETTERS in the range  it's column,row
but when using Cell NUMBERS, it's row,column.

Does it work  now?