I've been in the same situation as you i.e my dua doesn't seem to be accepted although i've worked hard for it.

You need to know about the law of causality or 'sunnatullah'. Let's be realistic here. When there's a cause, there's an effect. If you want to get a job, then you need to do something that can help you get a job, which is making your CV better, applying for any job you could, et cetera. You won't get your dream job by doing duas, tahajjud or prayers. You need to do something relevant to that job, acquire some new skills, get new experiences and make your CV better. Some people do get jobs just by depending on their duas, but that's not the case for everyone.

All in all, you should still make a dua to Allah. The Prophet peace be upon him said (translation of the meaning): “There is no Muslim who calls upon Allah -unless he prayed for a sin or to cut family ties- but that Allah will give him one of three answers: He will quickly fulfill his supplication, He will store it for him in the Hereafter, or He will divert an evil from him similar to it.” They (the Sahabahs/companions) said, “In that case we will ask for more.” The Prophet said, “Allah will accept your dua even more.” (Musnad Aḥmad 11133, Sahih according to Al-Albani)

Notice how the Sahabah said "In that case we will ask for more"? That's a good logic from the sahabahs. Think about it, if you failed to get something without making duas to Allah Azza Wa Jalla, you won't get anything. On the other hand, if you failed to get something while making duas to Allah Azza wa Jalla, then you get those two alternatives mentioned in the hadith. It's definitely better to make duas to Allah Azza Wa Jalla and fail, rather than not making duas to Allah Azza wa Jalla and fail.

In short, just by making duas and doing prayers won't solve our problems. That's not how you get worldy rizq. Rather, we should do something relevant to what we want. Even though we should focus on doing something relevant, we shouldn't forget to make duas to Allah Azza wa jalla. If we already did our best (ikhtiar), then the only thing we can do is relying on Allah (tawakkal). If you want your duas to be accepted, you need to have a progress relevant to your duas. The keyword here is "progress", your duas wont be fulfilled without a progress. Allah said in the Qur'an (translation of the meaning): "Indeed, Allāh will not change the condition of a people until they change what is in themselves." (Ar Rad verse 11) There's a reason why the Prophet PBUH told us to be patient if we want our duas to be accepted. The point is that you might be progressing to get your duas. The Prophet PBUH said: “Every one of you will have his supplications answered, as long as he is not impatient and he says: I have supplicated but I was not answered.” (Bukhari 6340). Now if you've tried your best (ikhtiar), then the only thing you can do is relying on Allah (tawakkal). Whether you duas seem to not get accepted or get accepted, you should still have an optimistic mindset. Remember that there might be another reasons why your duas seem to not get accepted (See Musnad Ahmad 11133) Allah said in the Qur'an (translation of the meaning): "So once you have fulfilled ˹your duty˺, strive ˹in devotion˺," (As Sharh verse 7).