How can I tell if a will is valid?

A will is only valid in Michigan if it is in writing, signed by the testator (the person making the will) or in the testator’s name by someone else at the direction of the testator, signed by at least two individuals, each of whom signed within a reasonable time after he or she witnessed the testator. A will can also be valid if it is in the testator’s handwriting, dated and signed by the testator.