Do you mean when using a program such as Word, or when you're on the internet?
If in a program such as Word, look for the 'zoom' option and make sure it's at 100% or bigger
If on the web, also look for the zoom option or quite simply press ctrl and +, which will zoom the size of the stuff you're viewing. Every time you press ctrl and + it will zoom some more. To make smaller again, press ctrl and - (the minus key)