it's my credit card, but i don't have it with me now and forgot the three digit security code ... In order to use it, i would like to see if i can try guessing the security code online till i get the correct one, but would this cause the card to be disabled due to suspicious activity?
This will largely depend on the vendor (online store) you are purchasing from. The 3 digit code, or CVV code, is an added check put in place for security. Whether or not the vendor accepts a card with a mismatched CVV code is up to them and their credit card processing company. Some vendors have set up their systems to issue an internal warning, but still process the payment. Others will block the attempted transaction altogether. Generally, if the shipping/billing address match the CC, vendors will still process the payment. They may disable your account (the website account, not your CC account) if they see too many attempts to make a purchase that are denied.
We can't give you a definitive answer here because it entirely depends on how the vendor is set up to process credit cards. The vendor may contact your credit card company to note that several attempts have been made to use the card, but it's not an automatic notification to the credit card company. Many credit card processing companies charge higher fees to the vendor if they don't have a matching CVV and zip code to process the sale, which is why they may choose to reject it.