Can't attend conference due to canceled travel grant
It may be possible, actually, to do more. You might ask if a remote presentation can be arranged. This is possible for some conferences, but would require some setup on your end as well, perhaps in coordination with the university. 

But for your actual question, yes, you can ask and explain the circumstances. Some conferences will say yes, some will say no, and some will have other suggestions. But it would be a mistake not to open a conversation with the conference committee. 



Note also that not showing up without notice will probably result in the worst possible outcome.