If your using Firefox ,up the top of the page should be the File, Edit, View,History etc etc menus . Select Zoom in or Zoom out from the drop down menu in "View " and then using the zoom feature adjust the page size. If your using Internet Explorer it should be much the same ,maybe different wording.
If still not working. try shutting your computer down completely ,turn off at wall and count to ten then restart ,it sometimes magically goes back to what you expect. good luck.