Are your plants dead or alive?
Not sure if your plants survived the winter? Some plants leaf out later than other so don’t be in a hurry to rip them out. The temperatures make a difference in when plants emerge from dormancy and some are always later than others. Hibiscus including Rose of Sharon are among plants that tend to be a bit late.
Besides patience another way to check for life on shrubs and trees: Beginning at the end of a branch gently scratch into the bark with a fingernail. If you see even a little green then the branch is alive. If you don’t see green continue along the branch scratching every few inches until you do see green. If you get all the way to the trunk or the middle of the shrub without seeing any green your plant or at least that branch is dead. Check on a second of even third branch in case it is just that branch.
Some shrubs die back to the ground each year (at least in certain climates). In that case the scratch test won’t help since everything above ground is dead anyway. You would just need to wait for new growth to emerge from the ground. Perennials usually die back also. If someone has the exact plant in your neighborhood and the same sunlight conditions and their plant is leafed out and yours has not there is a likely chance that your did not survive.
If you are still not sure and your plant is not large, carefully dig it up and look at the roots. Are the roots flexible and light colored in places or are they hard, easily broken, and black or dark brown? If the former, replant and wait a bit longer.