Connect to your serveur with SSH.
Go to the Limsurvey's folder
Type :
php application/commands/starter.php resetpassword NEW_ADMIN_NAME NEW_ADMIN_PASS
(replace new admin and new password with correct values).

I get this error:
Error: Call to undefined function gT() in /home/usabilit/limesurvey/application/models/User.php:107
Stack trace:
#0 /home/usabilit/limesurvey/framework/db/ar/CActiveRecord.php(604): User->attributeLabels()
#1 /home/usabilit/limesurvey/framework/validators/CValidator.php(250): CActiveRecord->getAttributeLabel('htmleditormode')
#2 /home/usabilit/limesurvey/framework/validators/CRangeValidator.php(84): CValidator->addError(Object(User), 'htmleditormode', '{attribute} is ...')
#3 /home/usabilit/limesurvey/framework/validators/CValidator.php(201): CRangeValidator->validateAttribute(Object(User), 'htmleditormode')
#4 /home/usabilit/limesurvey/framework/base/CModel.php(159): CValidator->validate(Object(User), Array)
#5 /home/usabilit/limesurvey/framework/db/ar/CActiveRecord.php(810): CModel->validate(NULL)
#6 /home/usabilit/limesurvey/application/commands/ResetPasswordCommand.php(24): CActiveRecord->save()
#7 /home/usabilit/limesurvey/framework/console/CConsoleCommandRunner.php(71): ResetPasswordCommand->run(Array)
#8 /home/usabilit/limesurvey/framework/console/CConsoleApplication.php(92): CConsoleCommandRunner->run(Array)
#9 /home/usabilit/limesurvey/framework/base/CApplication.php(185): CConsoleApplication->processRequest()
#10 /home/usabilit/limesurvey/application/commands/console.php(64): CApplication->run()
#11 {main}