Student or Learner
Do you say, "I looked hard for my glasses, but I couldn't find them"?
If it's wrong, what adverb should I use?
It is quite correct colloquial speech.
"I looked hard for you in the crowd, but couldn't see you."
I looked all over for... (You might use this expression if you had shopped in many stores all over town, looking for a particular item of clothing eg
I looked all over town for something suitable to wear to the Queen's Garden Party and couldn't find anything. I'll have to wait till I get to London and try Harvey Nicks."