Nadya,
REPLACE y.Whatever ...
Will only do a replace if ...
1. There is a table or cursor open in the currently selected work area
2. There is at least one record in that table or cursor
3. That table or cursor is not at EOF()
Unless you include the IN Y option on the REPLACE command line.
Also, using single letters as table alias' is a very bad idea, you should use at least two character because VFP's default alias' for certain work areas are single letters.