If your blanket has a cover . . . Unlike doona/duvet covers, the covers for our weighted blankets have little ties on the inside to prevent bunching in the middle.
Unzip your cover and turn it inside out, then feed the ties through the small loops on the corners and the sides of the blanket.
It’s easiest if you start at the end furthest from the opening of the cover and work your way back, turning the cover right-side-out as you go.