Error messages and can't log in

Hi,

I haven’t logged since the latest update last Fri (which happened automatically). Now I get these two error msgs:

Notice: get_currentuserinfo is deprecated since version 4.5! Use wp_get_current_user() instead. in /home/lesfem5/public_html/wp-includes/functions.php on line 3658

Warning: Cannot modify header information – headers already sent by (output started at /home/lesfem5/public_html/wp-includes/functions.php:3658) in /home/lesfem5/public_html/wp-includes/pluggable.php on line 1171

Searched and googled both and tried to follow suggested steps as much as I could (cleared cookies and cache), but I don’t know anything about coding or how to even FIND the code to apply the suggested fixes. (Tried logging in via FTP, not that I even know what that is, but it wouldn’t accept my username or PW (and I tried all possibilities, including my hosting co & cpanel info.)).

On top of it, I can’t log into wordpress AT ALL because it doesn’t recognize my username, email or password. I checked my hosting site (inmotion) and it says everything is all there.

Dunno if this is helpful, but this is the site: http://lesfemmesfatalesnyc.com/

Any suggestions before I kill myself?

Thanks so much!