I have an echo tiller/cultivator that will not start. As in you cannot even get the pull to move. So my question is - what have I done and how doe I fix it?

If the cord will not pull the tiller head is jammed trying to pull the cord will just break it . You must try and free the head. Try penetrating oil on the head leave for at least an hour then try cord again if not more spray

You will very likely have to take it in to a repair service and have it fixed.
For a lot of money, unless you have a friend that can do this. Since tiller/cultivators are seldom used, they always need to be "prepped" before they are stored.
That includes squirting a bit of oil into the combustion chamber and turning it over by hand to lubricated it, both at the end of the "use season" and at the beginning of the next year "use season". Also, be certain when you store it, to tip your machine is such a fashion as to cause the spark plug to be higher than the crankcase oil supply, or the oil will seep into the combustion chamber and prevent it from starting, because oil will not compress.
God bless your efforts.

If the pull rope won't move then the engine is locked up. There are many reasons. There could be internal damage, running the engine with an improper fuel /oil mixture if it is a 2 stroke engine. It is possible the gear and the transmission that drive the tiller tines is locked up too.Disassembling the tiller will be necessary to investigate the real reason the engine will not move.

Take spark plug out pull rope to start if you still cant pull starter then rope is off pulley or jammed up