Cannot log in to admin page

The problem is in your chosen theme. Try switching to the default theme by renaming your current theme’s folder inside wp-content/themes and adding “-old” to the end of the folder name using FTP or whatever file management application your host provides.

Thank you, I did that, everything worked fine, just downloaded the new wordpress update and my website is working fine, but the admin page is still having problems once I took “-old” off my theme folders name. Will I have to leave it like that or ?

Here is what’s popping up now:
Warning: Cannot modify header information – headers already sent by (output started at /home/content/d/w/4/dw4526/html/wp-content/themes/Gulf4Sale/functions.php:1) in /home/content/d/w/4/dw4526/html/wp-login.php on line 368

Warning: Cannot modify header information – headers already sent by (output started at /home/content/d/w/4/dw4526/html/wp-content/themes/Gulf4Sale/functions.php:1) in /home/content/d/w/4/dw4526/html/wp-login.php on line 380

Warning: Cannot modify header information – headers already sent by (output started at /home/content/d/w/4/dw4526/html/wp-content/themes/Gulf4Sale/functions.php:1) in /home/content/d/w/4/dw4526/html/wp-includes/pluggable.php on line 680

Warning: Cannot modify header information – headers already sent by (output started at /home/content/d/w/4/dw4526/html/wp-content/themes/Gulf4Sale/functions.php:1) in /home/content/d/w/4/dw4526/html/wp-includes/pluggable.php on line 681

Warning: Cannot modify header information – headers already sent by (output started at /home/content/d/w/4/dw4526/html/wp-content/themes/Gulf4Sale/functions.php:1) in /home/content/d/w/4/dw4526/html/wp-includes/pluggable.php on line 682

Warning: Cannot modify header information – headers already sent by (output started at /home/content/d/w/4/dw4526/html/wp-content/themes/Gulf4Sale/functions.php:1) in /home/content/d/w/4/dw4526/html/wp-includes/pluggable.php on line 876

Now no access to website or admin, this is what I receive:
Parse error: syntax error, unexpected ‘}’ in /home/content/d/w/4/dw4526/html/wp-content/themes/Gulf4Sale/functions.php on line 231

Now no access to website or admin, this is what I receive:
Parse error: syntax error, unexpected ‘}’ in /home/content/d/w/4/dw4526/html/wp-content/themes/Gulf4Sale/functions.php on line 231

This problem fixed

first problem still exists

Here are the errors that appear when I login and the line of code:

Warning: Cannot modify header information – headers already sent by (output started at /home/content/d/w/4/dw4526/html/wp-content/themes/Gulf4Sale/functions.php:1) in /home/content/d/w/4/dw4526/html/wp-login.php on line 368

header(‘Content-Type: ‘.get_bloginfo(‘html_type’).’; charset=’.get_bloginfo(‘charset’));

Warning: Cannot modify header information – headers already sent by (output started at /home/content/d/w/4/dw4526/html/wp-content/themes/Gulf4Sale/functions.php:1) in /home/content/d/w/4/dw4526/html/wp-login.php on line 380

setcookie(TEST_COOKIE, ‘WP Cookie check’, 0, COOKIEPATH, COOKIE_DOMAIN);

Warning: Cannot modify header information – headers already sent by (output started at /home/content/d/w/4/dw4526/html/wp-content/themes/Gulf4Sale/functions.php:1) in /home/content/d/w/4/dw4526/html/wp-includes/pluggable.php on line 680

setcookie($auth_cookie_name, $auth_cookie, $expire, PLUGINS_COOKIE_PATH, COOKIE_DOMAIN, $secure, true);

Warning: Cannot modify header information – headers already sent by (output started at /home/content/d/w/4/dw4526/html/wp-content/themes/Gulf4Sale/functions.php:1) in /home/content/d/w/4/dw4526/html/wp-includes/pluggable.php on line 681

setcookie($auth_cookie_name, $auth_cookie, $expire, ADMIN_COOKIE_PATH, COOKIE_DOMAIN, $secure, true);

Warning: Cannot modify header information – headers already sent by (output started at /home/content/d/w/4/dw4526/html/wp-content/themes/Gulf4Sale/functions.php:1) in /home/content/d/w/4/dw4526/html/wp-includes/pluggable.php on line 682

setcookie(LOGGED_IN_COOKIE, $logged_in_cookie, $expire, COOKIEPATH, COOKIE_DOMAIN, $secure_logged_in_cookie, true);

Warning: Cannot modify header information – headers already sent by (output started at /home/content/d/w/4/dw4526/html/wp-content/themes/Gulf4Sale/functions.php:1) in /home/content/d/w/4/dw4526/html/wp-includes/pluggable.php on line 876

header(“Location: $location”, true, $status);

Yes, that’s an error (or more) in the functions file of your theme – you’ll need to ask whoever made the theme to help you with it.

Thank you for your reply.
I found out that a .php file had a link to some payday loan website, that I believe appeared from a previous WordPress update. I removed it, yet I left a space before <?php which caused the problem.
All is well now.