I seem to have lost information on all but one of my customers. Why is this and how can I fix it?

Hello Mwrightatvservic, 

Welcome to the community page, 

Can you try some troubleshooting to see if this resolves your issue? 

Can you clear your cache and cookies, close the browser down, reload it and log back into qb and see if the information is there. 

let us know how you get on.