it seems that my proxy is always active. If I disable manual proxy configuration it turns on again. I've tried to delete some registry keys but the same keys appear again.
Here is the screenshot of Proxy Settings:

Here is the screenshot of Internet Option settings. In Connection tab Lan Settings Button is disabled.
Here is the regedit settings i've changed:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings
MigrateProxy
ProxyEnable (which is always set to 0)
ProxyHttp1.1 (which is always set to 0)
ProxyOverride (<-loopback>)
ProxyServer (which has the 127.0.0.1:8080 IP & currently I've deleted it)
Thanks for helping.