I’m angry and confused

Photoshop: Filters disabled, grayed out, not working

i bought Photoshop cs5 and it worked great for a long time then some of the filters quite working. when you go to the filters drop down menu there are more expandable options like artistic blur, brush strokes, render, etc. but instead of being bold the words are a grey color and i can't click on them to expand. some of the filters work and some don't. like render i can click and have it expand but then the lens flare option is grey and unclickable. i uninstalled it and reinstalled it 2 time and it didn't fix it.
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