If you don't know the bracha for food, say 'sh'hakol' if you don't know the bracha in another situation, say a full line from tehilim which praises Gd in a generic way.

In general the a more detailed bracha is always preferable over a generic bracha. This is why we have so many different berachot, to be as specific as we possibly can. However, if you do not know what the correct bracha to make is, you can make a more generic bracha.

The most generic bracha for food is "Shehakol" (from which all things are created). For other situations, the best practice is to say a pasuk from tehilim which generically praises Gd, such as "Hallelyuah"