Since the roots are in the top 4" or so, the incident must have been "traumatic" for the roots. I would give it TLC and see. They are tough plants and it may recover given enough time. You may need to stake it to stabilize it if heavy winds crop up. Not sure (pics are too far way) to see if the yellowing is iron chlorosis (yellow leaf with dark green veins) or a mineral defficiency (leaf turns all yellow).

Thanks for yr reply.

When the plant toppled over with the weigh of the snow, it tilted to one side. The roots on the other side stayed in the ground. But clearly the damage is throughout the entire plant. So I guess all the roots were damaged.

Here is a close-up of the leaves I took a month ago. It looks to me that it's iron chlorosis. If you agree, is there any treatment I can give the plant??

I've been pruning dead branches. Should I continue doing that? And pruning branches with dead leaves?

Thanks so much!

Is your soil sufficiently acidic to support the rhododendron? Iron is bound up if the soil is not adequaletly acidic and chlorosis results. Appying chelated iron products can help but is really a stop gap method unless the pH is addressed.

With rhodies, it doesn't really matter if the branch is dead or not before pruning. Very leggy or sparsely foliated rhododendrons are often pruned back hard overall to stimulate growth of the latent buds located up and down the stems. However I might not be inclined to prune yours now....instead, give it time to recover from the stress associated with the root disruption first before you stress it further by any hard pruning. Dead wood can be pruned out at any time.

In the past, the plant has produced a profusion of blooms every spring (the pic below is from past years). The leaves have looked healthy as well. So I think the soil conditions are right. Is there anything further I could do to address the pH in terms of modifying the soil or adding acidic content to it to improve its recovery process?

Just make a habit of applying the soil amendment. Either per label directions or when you notice the leaves starting to turn light green or yellow & the leaves' veins remain dark green. I apply it always in the Spring and it seems to last until the Fall or until the following year (so it varies). I also add some organic compost as a fertilizer on some years and it seems to help keep things from getting too alkaline. If you forget to apply it for long periods of time, the soil will revert back to its non acidic level so, it is best to amend with some regularity.