No access to inbox , could not read the mail


Forum Members.... I am a new member today( 17th Dec,2013) and wish to ask a solution of problem I face with gmail Inbox. I have this account since last 5 years. It was working well. But yesterday late-night, I was surfing the system settings in Mail section. Unknowingly, I guess that, I have done some blunder ( changed setting)there and today I could not read my emails from the inbox. I could see the mails is received but can't read it.. Can anybody who is well versed with email technicality, suggest me the reason and solution of the above problem ???