My paypal account is Business type, i added and verified my credit card, createad BuyNow paypal button added it to my website and when someone tries to pay there is no option to pay with credit card, only with paypal account.
Can you provide a screenshot of what you're seeing when you're sent to PayPal from your button? Also, can you do it from a separate browser that you don't typically use and see if it looks any different?
PayPal Standard (which is what the buttons use) only provides the Guest Checkout option based on browser cookies. If anybody has signed in to a PayPal account using the current browser, then a cookie is set so that next time they are sent to PayPal it assumes they'll be logging in with PayPal and won't need the Guest Checkout option. If you clear the browser cache/cookies you should see the Guest Checkout option come back.
If you switch to the Express Checkout API instead of PayPal Standard, then you can actually force the Guest Checkout experience regardless of any browser cookies. You have to do this with the Classic API, though, as that functionality is not yet available in the REST API.
Basically, in your SetExpressCheckout call you just need to include the following parameters: