If you have a flower which will not open and looks similar to this the rose it has the fungal problem of Botrytis. Botrytis is a fungus which forms on the rose petals and sticks them together stopping them from opening normally. Occurring mostly in wet climates and when the rose petals are particularly thin and soft.
There is little that can be done when a rose has been affected however prevention is the best solution. When selecting roses for a garden where constant moisture can be present ask the supplier if the rose may be prone to Botrytis, or if the rose flower has soft petals and may be affected. Some suppliers may not know this information however rose experts should know immediately what petal strength any particular rose has.
Fungal sprays can help in limited ways however if conditions are right there is little that can be done. Best to cut off infected flowers and wait for the next flowering which is likely to be better.