i cannot turn on my iphone 5s becouse i lost my passcode

try connecting to it in iTunes and maybe you can reset password then

If connecting it to iTunes doesn't unlock it, you will need to use the restore button in iTunes to erase it and restore it. If you have been using iCloud for backups you should be able to restore from iCloud backup, which will put all of your information back on the phone but will not remember the pass code and you'll be all set to make a new one. If you have been making backups to iTunes, then you can try to restore from the backup when it prompts you to in iTunes, but it will remember the pass code afterward and still be locked.

This is the only way

Forgot passcode for your iPhone, iPad, or iPod touch, or your device is disabled - Apple Support

it is a security device to protsect the contents

TheBig Ragu wrote:

try connecting to it in iTunes and maybe you can reset password then

Almost. You cannot reset the passcode, except by erasing all content on the phone. You can do that with iTunes, but unless you have a backup all data on the phone will be lost.