I've just run over a stone edge and it cut out and now appears to be 'locked'. The blade is intact and doesn't appear bent/twisted - but the cord pull wont pull out much so I can't turn over the engine and re-start!
Are you sure that the blade tip isn't jammed against the mower housing? If it is, this indicates that the crankshaft is bent, and that means a replacement engine. About £80 fitted.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix lawn mowers.