I have central heat/air and do not have heat coming through all of my vents, only some vents. It is a doublewide mobile home. What can I do?

Double wides come in 2 halves, the furnace is in one side and a flexible crossover duct ids installed to the other side,

Sometimes these come apart sometimes animals get into these pipes because they are warm.

Remove a piece of skirting near the furnace and see if this duct is intact.