You need to repair your amp.
Take the MONEY from the shelf above the books. Leave the room on the south and use the door on the right to enter the toilet. Take the TOILET BRUSH and leave the toilet again. Use the door on the north to go outside. Talk to the salesman in the stall on the right to buy a TICKET. Now you must find another 100 HUF. Use the sleeping homeless guy next to the stall to take 60 HUF from him. Use the ticket on the trolleybus to leave to town.
Use the door of the gate next to the punker to enter the studio. Use the door on the right to enter the rehearsal room. There’s a box of CIGARETTES on the amplifier and a DRUMSTICK in the trash can. In the back, right of the door is a brown mess. Use the toilet brush on the mess to clean it and find a KNIFE underneath.
Use the door in the lower left to leave the rehearsal room and walk to the north to go outside again. Give a cigarette to the punker and he’ll pay you 50 HUF for it. Use the door of the gate again and inside give the money to Szurdi. He still won’t help you since the toilet needs repairing first. Walk to the north again and outside walk to the north around the building to return home.
Use the door on the left to enter your house and use the door on the right to enter the toilet. Use the knife on the CORD to flush the toilet. Leave the toilet, use the door on the north to go outside and use the ticket on the trolleybus again to return to the studio. Open the door in the gate and inside give the cord to Szurdi. He still won’t help you. Give him a cigarette and he’ll give you a FUSE.
Use the door on the right to enter the rehearsal room again and use the fuse on the amplifier on the right to repair it. Now you can play again.
Game source: A copy of the game was found here on the internet.