The email page set up is missing scroll bar on right side-?

was request 1 day ago to change passwork did that, when trying to view mail today, my cursor locked on to the bard that divides the email options on the left w/ the list of emails to read- I mistakenly moved the cursor to the right side of page- resulting in a total eliminate of viewing any emails messages. Called yahoo to try to retrieve the messages- they sent this to their support people. When I tried to view my emails on another computor I could read them easily- hence is it not a case of missing emails but a case email page setup. what to do?? Chris