unserialize(): Error at offset 137 of 65535 bytes in /home/l

Pls help,

I cannot login into admin... below is the error on the backend (admin page when i log in)

Notice: unserialize(): Error at offset 137 of 65535 bytes in /home/lapmumbai/public_html/index.php on line 56
Warning: session_start(): Cannot send session cookie - headers already sent by (output started at /home/lapmumbai/public_html/index.php:56) in /home/lapmumbai/public_html/system/library/session.php on line 12Warning: session_start(): Cannot send session cache limiter - headers already sent (output started at /home/lapmumbai/public_html/index.php:56) in /home/lapmumbai/public_html/system/library/session.php on line 12Warning: Cannot modify header information - headers already sent by (output started at /home/lapmumbai/public_html/index.php:56) in /home/lapmumbai/public_html/index.php on line 175Warning: Cannot modify header information - headers already sent by (output started at /home/lapmumbai/public_html/index.php:56) in /home/lapmumbai/public_html/system/library/currency.php on line 45

below is the error on the front end, site is working with this headers, my site
http://loanagainstpropertymumbai.com/
Notice: unserialize(): Error at offset 137 of 65535 bytes in /home/lapmumbai/public_html/admin/index.php on line 41
Warning: session_start(): Cannot send session cookie - headers already sent by (output started at /home/lapmumbai/public_html/admin/index.php:41) in /home/lapmumbai/public_html/system/library/session.php on line 12Warning: session_start(): Cannot send session cache limiter - headers already sent (output started at /home/lapmumbai/public_html/admin/index.php:41) in /home/lapmumbai/public_html/system/library/session.php on line 12Warning: Cannot modify header information - headers already sent by (output started at /home/lapmumbai/public_html/admin/index.php:41) in /home/lapmumbai/public_html/system/library/currency.php on line 45Warning: Cannot modify header information - headers already sent by (output started at /home/lapmumbai/public_html/admin/index.php:41) in /home/lapmumbai/public_html/system/library/response.php on line 12