You've given us almost no information to help you.
Please tell us what operating system (exactly) you're running. Please tell us (exactly) what InDesign version you're using. What font is glitching (exactly - what it shows in the Type > Find/Replace dialog - screen capture would be good). We need a screen capture of what characters are missing.
There are many possibilities of what could be happening. Does this happen in just one file, or in every file that you try?