Customer service jobs come in a lot of different types, including call centers, technical support, or even things like working business-to-business customer service, with various names.  Hit the job sites, find the career sites of companies near you, and try to use keyword searches.  You might also consider trying to do some temp admin work to get some experience in office work that'd translate to an entry-level office job.  It's good if you can't run around, since you mostly work from a chair.  And given that you are a person who can get through a whole resume/cover letter without making spelling/grammar errors, you should be able to find people willing to at least give you a chance to interview.  After that, it's up to you to impress them.

I think you'd be wonderful in a library, S_C.