from text file to table

Dear Friends

I have a grid in my vb form the columns contain CustomerId, ProductCode, QtySold, Value. There may be more than 5 rows. I have 3 cmd buttons letus call NextCustomer, Recall, Save. They have to do the following actions.

1. When NextCustomer button pressed all the data filled in the grid should write (Append) in a text file in the client machine.

2. When press Recall button the last written rows only come to the grid and remove from the text file.

3. when i press Save button all the data should go to my database table.

help me how i do these actions.

my aim is to write all the sales entries in a text file (provision to modify) by customerid and finally update it to a table (not individually)

pl help

thanks in advance
bobbytom