Diana, usually not being able to taste salt is due to a lack of the correct amount of zinc in your body. Try a multivitamin or zinc supplement and give it about 3-4 weeks.
If you still can't taste salt then you might have a condition called "burning mouth syndrome."
It is not a serious condition and can be diagnosed by your physician however there is no known cure for it. It's cause is also unknown.
Most of the time it resolves within a year. It is one of those odd diagnoses that we don't know much about.
Google burning mouth syndrome to get more information about it.