Is your form's recordsource bound to the table or a query? Did you rename a field and forget to change the recordsource to the correct name? For example, instead of ClientName maybe it was Client Name with a space, or Client_Name with an underscore.
If you select your table from the drop down in the form's recordsource property you will find it all fixed. But, you should use a query instead of the table, so look here
If you select your table from the drop down in the form's recordsource property you will find it all fixed. But, you should use a query instead of the table, so look here