How can i fix my indesit cooker?

Hi, my cooker used to light but only two of the burners on the hob have ever lit and those are the 2 on the left. The cooker started going out but would always come back on when re-igniting but now we cannot get it to stay on at all. It will do the ignition but then as soon as you release the oven knob it dies out. We have just changed the thermo couple as we thought that this was the problem but we still cannot get the flame strip to stay alight when the knob is released. Plz help, i hav 6 kids and need a working cooker. Thanks. x