Don't feel bad. My browser keeps login data and sometimes I look through it for fun and to prune some old stuff. I found a Bitcoin address that had been used to login into some wallet site or something last year and actually had several of my old addresses stored in there.
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If you're talking about blockchain.info (now blockchain.com), there's chance you could recover your Bitcoin. AFAIK blockchain.info send email contain backup of your wallet and wallet identifier used to login, so you might want to check your mail.
Unfortunately most exchanges in early days (including Cryptsy) is long gone due to various reason.
But, one thing to think about, if you have the computer where the wallet.dat was stored and you have not completely reset your OS, there is software, and some free, that can recover lost or deleted files, and with decent luck if not much time has passed. I deleted a file that had my corporate credit card info in it, and got the files back in less than an hour, including the time to Google the software, install it and run it.
Fortunately almost all "delete" action actualy don't delete the files, but only mark it as "deleted". It'd be more difficulty if you copy lots of files to HDD/SSD where the deleted files is located.