Forms don't have to be linked to tables, but if you mean the table that
provides the data for your form, you probably need to update the 'record
source' property.
Click View--Properties--Data--Record Source
Open the form in design view.
Point the cursor at the upper left corner of the form.
Right click and select Properties from the drop down menu.
Look at the top of the properties dialog to be sure you have the properties
for the form and not some other object.
Select the Data tab.
Enter the name of your table in Record Source.