Bler can mean two things depending on the pronounciation of it. Under the first pronunciation it can be used to mean a stronger version of the word "bleh"
Under the second it can be a combination of the words "bleh" and "errr" to mean a sort of depressive "duh!"
This word comes from a mispelling of the word "bleh" that seemed to fit the randomness of the conversation
1. Holy shite, today my girlfriend broke up with me and my parents kicked me out, not to mention I have the flu. I just feel so...bler
2. Oh my gosh, I failed my test because I thought that 4x8=16....blerr!