Could you explain to me the difference between "refuse" ,"reject" and "refute"?
'Refute' is easy-- it is used mostly of argument, and means the offering of proofs or evidence against a statement or belief.

'Reject' and 'refuse' are not so easily separated, even though the phrase 'reject and refute' repeatedly occurs in religious and quasi-legal Englishes. They are often used interchangeably, and I have an idea that choice in use is often idiomatic.

Some common collocations:

Refuse admission/a second helping
Refuse/reject an offer
Refuse/reject a gift.
Reject an excuse/an application/a suitor

It occurs to me that 'refuse' means 'not to admit', while the stronger 'reject' (as its Latin root reveals) means to 'throw back' forcefully.

Perhaps another member will be more lucid on this topic.
refute: disprove (a statement or argument); demonstrate that a statement is false

I say that the word "strawberry" comes from "straw" and "berry", a berry found in straw. Can you refute my claim?

refuse: say "no" to an offer; opposite of "accept" (say "yes")

I offered to help Bill load the wood onto the truck . He refused my offer to help. He refused help. On the other hand, Pete always accepts my offers of help.

refuse: say "no" to a request; opposite of "consent" (say "yes")

I asked George to contribute a dollar. He refused to contribute anything.
Fran requested that all employees attend the meeting. All of them consented to attend. None of them refused to attend.

refuse: not consent; be unwilling; won't (wouldn't)

Jan is impossible to work with. She absolutely refuses to cooperate. She won't cooperate.
Her husband was lazy. He refused to do any work around the house. He wouldn't do any work around the house.

reject: react negatively, even with hostility, to a proposal, idea, offer, etc.

Paul was quite surprised when Laura rejected his suggestion that they vacation in Hawaii.
The people rejected the candidate's bid for the presidency.

reject: completely refuse to believe

Tom rejects the idea of global warming.

reject: not to accept (personally, socially)

After a long and heated argument, they decided to ban him from the club. He felt rejected for weeks.
Sam tried everything he could to make Ellen like him, but she always rejected him. She rejected his kindness. She rejected his advances. She rejected everything he stood for.

Hope that helped.