It means that they have already suggested some solutions and right now nothing more crosses their mind and they are run out of solution and sort of are fed up

It seems like the author have done his/her best to solve the problem(s) but he/she does not know any other solution "except" his/her previous ones.

Suppose that you're in a situation full of troubles and the troubles are getting serious increasingly and you're confused what to do. In such a situation, you say: من که دیگه نمیدونم چه کار کنم This "dige" is what you're asking about. Although it could be omitted from the sentence, It means that I used to know what to do but since the problems are getting serious, from now on I don't know what to do.

there are many meaning about 'digar' or 'dige' in persian, i tell you some different sentences using 'دیگر' or 'دیگه' to more understanding: sometimes in serious situation: 1) i can't stay: نمی توانم بمانم i can't stay anymore: دیگه نمی توانم بمانم or i can't stay more than this: بیشتر از این نمی توانم بمانم/دیگه نمی تونم بمونم بس کن: stop دیگه بس کن: don't continue anymore some times for emphasis: باید ازدواج کنی: you should get marry دیگه باید ازدواج کنی: that is exact time to get marry and other meaning also....

Suppose that you're in a situation full of troubles and the troubles are getting serious increasingly and you're confused what to do. In such a situation, you say: من که دیگه نمیدونم چه کار کنم This "dige" is what you're asking about. Although it can be omitted from the sentence, It means that I used to know what to do but since the problems are getting serious, from now on I don't know what to do.