A job loss does not affect credit scores. What affects credit scores is not paying your bills, having your home foreclosed on, any liens on your home, etc.
You could have avoided a low credit score. After you lost your job, did you cut all your expenses to the bone - no you did not. If you owned your home, did you try to sell it & move into a rental - no you did not. Instead you chose to continue living as if you were still employed. That was your biggest mistake. Again, your job loss had nothing to do with your low credit score. Now you're suffering the consequences.
Sorry but landlords are running a business. They don't want to rent to people with low credit scores. You will need to prove that you have been paying your bills on time every month & what are you doing to improve your credit score? Having a co signer is not enough. What will work is if you can pay 1st & last month's rent upfront + 1 month's rent as security deposit.