well as it isn't dead then yes give it lots of tlc [water in particular]. in a week or so cut out any dead wood where there is no leaf growth and give the ground around it some growmore type fertilizer too.
did you gat a sudden sharp frost? that would affect the blossom.

I would add that if you only planted it last year and had a crop of plums it could have sapped its strength, it wouldn't have much of a root system in place to support it...
i would do as Seaburn suggests and make sure its well watered all summer, what you do this year affects next years crop.....

Thank you both for your helpful responses. I am relieved that you do not feel that all is lost and Czar might live to crop another year, if not this one.

Plums can be quite slow to settle down but as long as it looks healthy then don't worry