Raspberry Pi OS is not starting after executing bad Shell Script

Question

Today I was trying to setup Owncloud in my Raspberry Pi, then I stuck when there is need to giving ownership or adding Owncloud file to www-data user and group. After trying all possible options I just opened the owncloud webpage to see what kind of error it generate, and I found the same ownership error and a suggested doc page where a suggested script is given, I executed it and after executing that script EVEN WHEN I AM ROOT I CAN ONLY USE cd COMMAND. If i execute other commands like ls it says access denied even when i am root.

Things I have.

1. Raspberry pi B+
2. 32GB Pendrive (FAT23 System) (Treated as cloud storage)

I already have configured apache web server.

3. I created alias of /cloud to point to /mnt/cloud/owncloud

Due to insufficient memory I placed all owncloud files in mounted directory /mnt/cloud/owncloud.

To change ownership of owncloud I tried

1. sudo chown -R www-data:www-data /mnt/cloud/owncloud Result : Operation cant be performed (I don't know why) (till this point I am unable to open owncloud index page
2. sudo chmod 777 /mnt/cloud/owncloud Result : Operation performed (after this command I am able to open http://192.168.192.99/cloud page. But problem is not still solved)

3. I found a suggestion on index page to open a owncloud documentation and try to resolve the ownership issue. Script is given below

   #!/bin/bash
   ocpath='/mnt/cloud/owncloud'
   htuser='www-data'
   htgroup='www-data'
   rootuser='root'
   
   printf "Creating possible missing Directories\n"
   mkdir -p $ocpath/data
   mkdir -p $ocpath/assets
   
   printf "chmod Files and Directories\n"
   find ${ocpath}/ -type f -print0 | xargs -0 chmod 0640
   find ${ocpath}/ -type d -print0 | xargs -0 chmod 0750
   
   printf "chown Directories\n"
   chown -R ${rootuser}:${htgroup} ${ocpath}/
   chown -R ${htuser}:${htgroup} ${ocpath}/apps/
   chown -R ${htuser}:${htgroup} ${ocpath}/config/
   chown -R ${htuser}:${htgroup} ${ocpath}/data/
   chown -R ${htuser}:${htgroup} ${ocpath}/themes/
   chown -R ${htuser}:${htgroup} ${ocpath}/assets/
   
   chmod +x ${ocpath}/occ
   
   printf "chmod/chown .htaccess\n"
   if [ -f ${ocpath}/.htaccess ]
    then
     chmod 0644 ${ocpath}/.htaccess
     chown ${rootuser}:${htgroup} ${ocpath}/.htaccess
   fi
   if [ -f ${ocpath}/data/.htaccess ]
    then
     chmod 0644 ${ocpath}/data/.htaccess
     chown ${rootuser}:${htgroup} ${ocpath}/data/.htaccess
   fi
   

Link for above code is Here

After executing this script All things are changed I am not able to use any other command then cd and I think to restart Raspberry Pi but it ends up in the state as shown in image

I don't know how to

1. Access the terminal now.
2. If terminal is accessible how to execute all command when i am Root