Please tell me whether it is a correct sentence or not?

[Rakesh]

she is asking for a like from you (like in the sense a like for a photo)

[Bala M]

Does not make any sense

[Nithin Baby]

no

[thegentle Indian]

WRONG.
I would re-write this way:
She is asking for a positive reply from you.

[Qasim]

WRONG.
I would re-write this way:
she is asking for a favour to you

[gary b]

In the context of Facebook, yes, the sentence is fine. The word "like" has a specific technical meaning on that site. Other social media sites have similar mechanisms. On Reddit, she might ask for an upvote. On YouTube, she might ask for a thumbs-up.

When there is no social media approval mechanism included in the obvious context, then no, that sentence is not very good. As you can see from the other respondents, it makes no sense when taken out of context.

Since you're talking about a like for a picture, I'm assuming that something like Facebook is involved.

Asking for a like on Facebook is fine. Asking for a like in person is just plain weird.

[Mohit]

No, even if it is in the sense of a photo.
The correct sentence will be:

She is asking you to like (her photo)