Salam
As for Wudhu yes and you need to repeat it.
As for Ghusl also yes, but you may be able to make it valid very easily.
So if this dry part is in your left side of the body you can make it wet with the intention of Ghusl and this way your incomplete Ghusl will become complete and valid (The reason is in Ghusl, Muwaalaat i.e. "not creating distance between the components of a task" is not a condition for validity but in Wudhu it is!)
According to Sayyed Khamenei if this dry part is in your right side of the body you have to make it wet and also wash the left side as well because in his viewpoint, the sequence of head and neck then right then left side has to be observed according to obligatory precaution. same is with the head and neck i.e. if the dry part is in your head and neck you have to repeat on right and left part again.
According to Sayyed Sistani, if this dry part is in your right part of the body also you can make it wet with the intention of Ghusl and there is no need to wash the left part afterwards.
But if it's in head and neck then you need to wash the body afterwards.