Unfortunately there is not much that we can do about this problem, the issue is normally with the printhead and it will need replacing. Unfortunately they are not always available though, have a look online but if you cannot see one then it’s likely not available. Even if it is available I would question whether it is actually worth replacing or not, most inkjets are essentially throwaway items so there are plenty of other problems you might encounter which you will not be able to resolve. If you get this sort of problem it is normally an indication that it has been well used, if you have stacks of ink and it is fairly new then maybe there is value in changing the printhead (providing it is available). If you have had it many years or used it a lot then it’s probably best to just replace the printer.