@Ohad_Assoulin For account specific things like this it’s best to contact our support team at email@example.com. Cut and paste your note above and make sure to include the email associated with the account (so the team can find your account). They will be able to identify the issue and get you up and running.
This often happens when one of the positions in the account becomes ‘untradable’ (ie delisted or some other corporate action). A price therefore cannot be found for the security and therefore the buying power and other values cannot be calculated. The, immediate fix which the Alpaca support team can help with, is to remove the untradable asset from the account. There is an engineering request in the works to avoid this error in the longer term by assigning a value of $0 to any untradable assets.