Hi & welcome Christina
Can you give us details of your grandfather? Name/date of death, age abode.
First place i would try is central library, they hold old newspapers which may hold his death notice/obituary.
Next i would give
Manchester Crematorium a ring, as these days many people are cremated because it is a little cheaper than a burial.
Did he live & die in the Manchester area? Or was he in one of the surrounding areas i.e. Salford/Stockport/Tameside and so on.
As you say you have tried the online burial site, i'll not post the site.
The more info you give, the better chance we have of helping you.
Migky