If you can get a roofing person ASAP, that will be choice one. Because the melting snow will continue creeping into the house. It's more expensive and messy to fix damaged dry wall and paint over water stains.
If you can not get one right away, since I guess your roof is of a low pitch (a less slopy one), you probably can get a ladder to remove the snow from the eave up to about 2 yards (say an area of 2x2 yrd.) This will help the roof dry out. You can also go to HD to get a tarp (~20'x15')to cover the part of roof, from the top ridge all the way down to the eave, and secure it with rope until the repairman arrives.
Leaky valley repair is not recommended for first time individuals(you could easily get things worse).
The repairman probably will remove some shingles and reinstall the valley flashings properly, but I don't you need to replace any plank wood. Ask the repairman if the roof has Ice and Water installed. If not, at least for that ridge ask him to install Ice and Water for the area that he will rip open.
If you can not get one right away, since I guess your roof is of a low pitch (a less slopy one), you probably can get a ladder to remove the snow from the eave up to about 2 yards (say an area of 2x2 yrd.) This will help the roof dry out. You can also go to HD to get a tarp (~20'x15')to cover the part of roof, from the top ridge all the way down to the eave, and secure it with rope until the repairman arrives.
Leaky valley repair is not recommended for first time individuals(you could easily get things worse).
The repairman probably will remove some shingles and reinstall the valley flashings properly, but I don't you need to replace any plank wood. Ask the repairman if the roof has Ice and Water installed. If not, at least for that ridge ask him to install Ice and Water for the area that he will rip open.