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That is most often caused by a valve in the toilet coming apart internally and blocking the water flow. The "fix" is to take the toilet off and replace it. There is a chance that it might be some lime or sand debris or debris from the fresh water tank doing this. If so, you would still need to remove the toilet and blow that out with some compressed air. Hope that proves helpful here. Please get back to me if you need more or want to attempt this yourself. Not very hard if you are somewhat handy with tools. Please include the make and model of your toilet so I know what we are working with here. All follow ups are included in our fee.
Just checking back to see if you were able to resolve this issue or do you still need some additional input from me here?