As the others have said, placeholders should be used.

Using placeholders won't fix your problem although it might make your problem more obvious.

Here is one of your sql statements:

INSERT INTO Repairs.computers VALUES (compManufacturer, compModel, com
+pModelNum, OS, errorMsg, serviceNeeded, problemDescription, barcode, 
+password) ($customer_compman, $customer_compmodel, $customer_compMode
+lNum, $customer_os, $customer_errormsg, $customer_service, $customer_
+probdesc, $customer_barcode, $customer_loginpw
[download]

Now we switch in the placeholders:

INSERT INTO Repairs.computers VALUES (compManufacturer, compModel, com
+pModelNum, OS,errorMsg , serviceNeeded, problemDescription, barcode, 
+password) ( ?, ?, ?, ?, ?, ?, ?, ?, ?
[download]

What's this? The VALUES keyword is misplaced and there is a missing closing parenthesis? Oh my.