Question about job offer I received?

If they were going to pay relocation expenses they would have offered it. Making those kinds of demands before you even start the job is a very bad idea & will probably get your job offer rescinded.

Unless the company provided housing under a company contract or lease (not some sort of funding toward relocation expenses), you are liable.

Subletting is always risky, and if you found the sublease & signed it, that's your problem. Your employer has no liability, and you have to dig yourself out of your mess. In fact, if you found the housing & signed, admitting to your employer how badly you fouled up could risk your job. You don't want to look like an idiot in front of a new employer.

If I didn't have the money to relocate, I wouldn't and politely decline the offer asap. The last thing I would do is admit my ignorance that led to getting scammed or demand my new employer to front me any money for it.

Asking for relocation money is typically done before you accept the job. Now is difficult time to do that.

Why would you negotiate a lower salary?

Unless you are able to borrow, your only option may be to crawl back and tell your new employer your situation and explain that you are financially unable to accept the position and let them decide if they want to offer you anything.

If you know the person you gave money to for the sublease, you should be preparing to sue in small claims court. The apartment complex that evicted him should be able to help with the name and possibly new address if needed.

If I were your new employer I would question your judgement based on the facts you have given us. If, after 9 years of work experience you have not learnt how to do basic due diligence before parting with your money and (apparently) have zero savings, you are not a good prospect.

What would I do? I would find some other way to get the money. Have you tried to negotiate with the landlord?

I would try to leave your employer out of this. Relocation assistance, if it was available, should have been part of the offer. Certainly don't negotiate a lower salary in order to get assistance up front.

If you can borrow from a friend or family member, that may be a good option. A more reliable bet would be to take out a small loan from a bank. This will come with a modest interest rate, but it will save you from potentially risking a relationship by borrowing from somebody you know.