>>>>>This query was working fine, but then all of a sudden it stopped pulling data. No errors, just empty results.
>>>>>
>>>>>

>>>>>SELECT Salutation.Salutation, Valid_Numbers.[First Name], Valid_Numbers.[Last Name], Valid_Numbers.[House Number] & " " & [Street Name] AS Address, Valid_Numbers.City, Valid_Numbers.ST, Valid_Numbers.ZIP, Valid_Numbers.[Date of Birth]
>>>>>FROM Salutation INNER JOIN Valid_Numbers ON Salutation.ID=Valid_Numbers.Salutation
>>>>>WHERE switch(Len([date of birth])=7,Left([date of birth],2)=Month(Date()),Len([date of birth])=6,left([date of birth],1)=Month(Date()));
>>>>>

>>>>
>>>>Are you using Access database? Have you tried running it in Access, not in VB? Also, have you checked if your tables still have data?
>>>>
>>>>Also, can you translate this complicated WHERE condition into English for me? What do you want to get?
>>>
>>>What is the format of the data within the [date of birth] column? Whatever guesses that I can make about the format don't seem to match the logic given in the switch() function.
>>
>>I suspect it is character, but let's wait for Jim to answer this question.
>
>Best guess I can make about the intent of the WHERE clause is to show records with people with birthdays this month.

In this case it's better to check this http://www.berezniker.com/content/pages/sql/microsoft-sql-server/birthday-query-ms-sql-server and adapt for Access.

Also, it is always a bad idea to store date as character. Someone even wrote a blog about it:

Dear ISV: You’re Keeping Me Awake Nights with Your VARCHAR() Dates