I can't sleep for 2 days n more, I need alganax, what should I do? I am very depressed

TREAT THE PROBLEM. Alganax is another term for xanax (alprazolam) which is not typically for sleep. So the question really is why can you not sleep? Is it caffeine, is it drugs, is it depression, is it bipolar disorder. Get an evaluation and treat the cause not the symptom.
Seek help. There are many things that you can do to help yourself sleep before using medication. They are called "sleep hygiene techniques" and include things like avoiding stimulant like chocolate, tea, and soda late in the day and regulating your light exposure. Consulting your doctor would be a good idea to learn more.
Sleep hygene. We r creature of habit , sleep hygiene is very useful tool to help u sleep , sleep medication can be used for a short period if time on as needed.
See a Doctor. Not sure what alganax is. You need a thorough evaluation asap. Meanwhile, melatonin may help a bit but don't do this instead of being seen.
Check with your PCP. It is important to check with your primary care physician first - to assess your general health. If nothing is wrong and you are still depressed, he may try anti-depressants, like ssris, or if your depression is severe enough, refer you to a psychiatrist.