Okay step back a bit here. Data is not stored in a query, it is stored in a
table.
The first thing you do in a database is build your tables. The tables are
where all your data is stored. The next step is to build queries, forms,
and reports. These are the items that allow you to view, modify, and add
data to the tables.
Typically, a form would be based off of the table (bound to it) if it were
simply used to enter data in the table. If you open the form in design-view
and look at the "data source" you'd see the table name listed there.
If the form is also used to view data, it will often be bound to a query.
The query can help filter out some records. For example, if your table has
a field in it called "inactive", you may want to create a query that will
exclude all the inactive records. Binding your form to this query would
cause the inactive records to be excluded from the form as well.
Now, back to my question...
1) In your form, what is the data source; what do you see in that field in
the properties box?
2) When you open the table (double-click it) do you see the "missing"
records? In other words, are the records that you think have vanished
actually in the table?