Can a unemployed student who is not working used his guardian's or parents' bank statement from his own country or the unemployed student must have his or her own bank statement? Even when the sponsor who lives in UK will sponsor the trip?
An unemployed student will have a very hard time to get a visitor visa, and if he needs a sponsor to have enough money for the visit it will become even harder.
For the visa you will need to show your own bank statements, showing how much money you have and how you handle the incoming and outgoing money.
If your sponsor is going to pay for all the travel, you will need to add their bank statements as well as a good reason for them to sponsor you.
And you will need a good reason to return home at the end of the visit. Having a ticket is not good enough, (and for most visa the UK advises not to buy a ticket till you have your visa.) Finishing off your study after your return will help a little but not much, as many students stay in a different country and either not finish their study or do it from the country they then live.
Better reasons are a spouse and children you support, (but as an unemployed student that is unlikely,) or having parents you take care of.
While there is supposedly no discrimination in this process, it is a fact that people from some countries have a much more difficult time that people from some other countries.
This is based on experience, who did overstay and disappear and who did go home at the planned time. Now the good suffer under the bad.
Going by your screen name I fear you are from one of the countries which have a hard time (but I might be mistaken.)