Fonts can be a little problematic to juggle and to have work all the time for various reasons if you aren't familiar w system reqs --
If you are having problems you may not have the right font file - they differ from mac to pc...for example, I have "suitcase'" and "postscript" and "truetype" fonts - and if a program cant find the one it needs it will give you an error -
If u run into a prob usually it is because u haven't dragged the right files to the right place -
Below is an example of a download and install process1. I went to misprinttype and downloaded a font called "broken". I now have a folder called broken that has a pdf, and two folders, containing pstype1 and truetype fonts ( I am on a mac - pc will be different)
2. I drag these folders containing the different types of fonts to my font folder - not my system font folder - but my own personal font folder. The system can get bogged down if you have too many fonts loaded - so I use a font juggler called extensis suitcase that allows me to activate the fonts I want to use, and deactivate the ones I don't need. You CAN use your system folder for now - just keep an eye on how many fonts you have open.
3. I open extensis. I add and activate
the "broken" font.
I test in photoshop and indesign.
Screenshots
A screen shot of the extensis window, activating the new font
Testing the font in photoshop

Testing the font in Indesign

Advice from a PC user
"If you're downloading fonts, you need to make sure you download them to the right folder (on Windows machines I think it's C:\Windows\Fonts). Also, just because the font is in the font folder that doesn't necessarily mean it's been "installed," but if you follow these steps, you shouldn't have any more issues.
1) Download, copy, or transfer your font to the Fonts folder.
2) Go to the Control Panel and open the Fonts folder. You should see the font (or fonts) you just placed there, along with all the other fonts that have been installed on your system.
3) Go to the File menu and select "Install New Fonts." The "Add Fonts" dialog box opens.
4) Make sure you're in the c:\windows\fonts directory, and then scroll the list of font names until you find the ones you've just added. Select one or all of them (click the "Select All" button to select everything in the folder, or CTRL mouse click to select more than one but not all the fonts).
5) Click OK. That should do it.
You don't really need to "open" a font file (unless you have a font creation program you'll just get gobbledy gook anyway), but you'll know if it's been properly installed if you open Photoshop or Word or any of your other programs, and you scroll through the font list. If it's on that list, it's been installed and you're good to go."