When someone has a will drawn up, but he's physically incapacitated to the extent that he cannot sign it, the law provides for this type of problem. In such a circumstance, you have options, but specific rules may differ from state to state.
Someone Else Can Sign for You
Some states, such as Washington, allow the testator -- the person who creates the will -- to ask someone else to sign his name for him. This individual must also sign her own name and make a notation that she executed the will for the testator because he asked her to.
Make Your Mark
If you can make a mark on the signature line of your will, such as an X, this will suffice in some states. For example, Texas allows you to do this if you go through all the same formalities as if you had been able to write your name. Two witnesses must watch you make the mark and they must sign their name to your will.
The testator must be of sound mind at the time of the signing – his impairment must only be physical in nature. In legal terms, he must have testamentary capacity. He must understand what he owns and he must comprehend his relationship with the beneficiaries to whom he's giving his property. He must understand that his will transfers his property to them at his death. Without testamentary capacity, the will can be contested and possibly invalidated by the court, regardless of how it's signed.