Take all the lamps out ( bulbs to you) lol and try to reset the breaker, The lamp that blew may still have a fault on it. If it resets then replace the lamps one by one. If you try one and it trips again you found your faulty one

If you have no lamps in and it still won't reset then it's probably a faulty breaker. Write the name of it and the size of it (probably 6 amp) and go to a wholesaler. They are about £6. If it's not a faulty breaker then your wiring is faulty and will need a sparky to test it. Hope this helps