A year ago, I was was appointed a treasurer in an organization. I used the money for my personal needs. I concealed the accounts and nobody realized what I had done. I repented of my sin and promised God to repay the money once I got a good job. I have not been able to repay the cash because I haven't settled in a good job. This is really tormenting me and affecting my faith. Please advise me on what I should do.
You stole money and while you regret what you did and are resolved not repeat your sin, you have not yet tried to undo the damage that you caused. Paul "kept declaring ... that they should repent and turn to God, performing deeds appropriate to repentance" (Acts 26:20). What is lacking is that you have done nothing that demonstrates your change.
Instead, you are inadvertently trying to bargain with God. You've set a condition on your full repentance: first you want a good paying job, then you'll return what you have stolen. Since you don't have a good paying job, then you imply that it is God's fault that you haven't fully repented.
Therefore, let's put this back in perspective. Start saving every little scrap that you can, even if it is not a large amount. Cut out anything that is not necessary from your life for a while and count that as the consequences of your sin. Each month send an anonymous cashier's check to the organization for the amount you saved up and include a note that you are paying back what you stole. Continue until you pay off the debt and I would suggest that you send extra to make up for the trouble you caused.
I suspect that if you go at this with full determination that you will find that it won't take you long to straighten out your past.