Theory:

I’ve searched through the recycle bin
And files of every kind;
I’ve even used the Internet,
But nothing did I find.
 
In desperation, I asked Jeeves
My searches to refine.
The reply from him was negative,
Not a thing was found ‘online.’
Explanation:
 
The poet says he has searched her in the recycle bin of computer wherein some deleted files go automatically. He also searched her through files in the drives and gone through the Internet. But he could not find his grandma. He became so hopeless that he even asked Jeeves, which is a widely used search engine that accepts plain English questions or phrases. But it did not give any valid reply. He couldn't find his grandmother online as well.
 
Meanings of difficult words:
 
NumbersWordMeanings
1.
Recycle binTrash for Android.
2.
DesperationDistress.
3.
Ask JeevesA widely used search engine.
Reference:
State Council of Educational Research and Training (2019). Term-1 English Standard-7. The computer swallowed grandma - Anonymous (pp. 16-17). Published by the Tamil Nadu Textbook and Educational Services Corporation.