pressure for boiler?

hi i've got a ideal isar boiler, the time pressure lever is down i dont know why, i also took some pressure out of the heaters. i rang the warmsure helpline, where I got the boiler fitted from, she told me to put the lever down to let water pass through, I done that but water wasnt passing. She said she couldnt, help me, I dont know if the boiler is useless or what. If there is anyone who could help it would be really appreciated.