You have two options at least:
1) Create another table with memo field, close it, and rename the memo file to the missing one:
CREATE TABLE NoMemotst (mmm M)
APPEND BLANK
USE
RENAME NoMemotst.FPT TO .FPT
USE
2) Open a copy(!) of the table without memo in hexadecimal editor and overwrite its heading information - change all Memo columns to e.g. Character columns. It is just simple change of "M" to "C" but you have to be familiar with haxadecimal representation of binary files. The DBF heading structure is described in VFP help.