Wills, probate, letters of administration, powers of attorney
You need grounds to contest a will.
Be aware that the estate was the property of the deceased to dispose of as they saw fit. However the law does impose a few restrictions on that.
The deceased has a responsibility to provide for care for a spouse and any minor children. Also any person who is suffering from a disability that the deceased was caring for in their life time.
Apart from that the deceased can give their assets to anyone they like, including the local dogs home.
To successfully contest you need to be someone who has an entitlement and who has been overlooked or insufficiently provided for. Just because you were related to the deceased is not sufficient grounds.