Unfortunately, if your shared hosting company cannot enable the proc_open() command, there is no way to fix this error as it is required by the Symfony Mailer package used by Laravel's password reset functionality.
Your best option would be to switch to a different hosting provider that supports this command or consider using a third-party email service like Mailgun or SendGrid to handle your password reset emails.
If you decide to use a third-party email service, you can update your Laravel configuration to use their SMTP server instead of the default mail driver. Here's an example configuration for Mailgun:
MAIL_DRIVER=smtp
MAIL_HOST=smtp.mailgun.org
MAIL_PORT=587
MAIL_USERNAME=your-mailgun-username
MAIL_PASSWORD=your-mailgun-password
MAIL_ENCRYPTION=tls
Replace your-mailgun-username and your-mailgun-password with your actual Mailgun API credentials. You can find more information on how to configure Laravel to use a third-party email service in the official documentation: https://laravel.com/docs/8.x/mail#driver-prerequisites