Hi i have a henry vacuum which my daughter used on wood/coal ash and now does not work.

OK... You are suggesting that Henry doesn't work because of what your daughter did with him. This may or may not be fair on your daughter! Depending on the degree of filtration in your Henry, he should be able to cope with ash (as long as it wasn't hot) without difficulty. Provided that your Henry had an undamaged cloth or paper bag, and that his "top-hat" cloth filter is intact, I think it unlikely that the ash is the cause of the problem. Many people use their Henry without a bag - this is a false economy, as dust always always finds its way in to the motor and, ultimately, that's terminal. Look at the underside of Henry's motor compartment (the black part) where the air goes in, and at the exhaust where the air blows out - if it's obvious that he's been sucking or blowing dust, you probably need to replace him. However, if bag and filter are intact, you probably need to look elsewhere for the source of the problem, and the first place to look is the electric flex (particularly for damage where it enters the plug). I hope this helps - but if not, please post a comment again and we'll look further. Good luck!