It's been five years since this query was posted and I don't know if Cheryl has retained her original e-mail address. If she has, Ancestry.com will inform her of this response.
If Cheryl can determine her mother's first name and date of birth, from interviewing relatives and/or inspecting her parents' marriage license, she can use a certain search engine which does not require a surname if the d.o.b. is known :http://www.people-finders.ws
The names and addresses of vital records offices that retain marriage license records are online at :http://www.cdc.gov/nchs/howto/w2w/w2welcom.htm