Build me a project

We used to have have an app ProNoor Notepad and paint. It was working and then something happened and the developer became sick. God knows what happened to him but we did our best to get in touch. We could not find the code part. So now we are thinking of making it a new. We will make it as a program first and use it as desktop/laptop app on all platforms. After that we will make it for androids and ios. A user will login on our site and will click on Notepad. Page one is for Text writes that can be saved and edited at all times. Page 2 is for drawings and paint. Each file can be saved and edited as needed. Page 3 is for Spread sheet. Admin will have option to add more pages Each user will have option to activate levels of security on each page from setting. He can enter the notepad with password, have a code entered or can have code sent for each security. All data saved on server will be encrypted and can be deleted from server if desired by user. You can suggest the Technology but it must be compatible with latest updates and easy to run on multiple paltforms. On Page 2 admin can add options to make drawings and paint easy and flexible for different level of users Working of all three pages: you can write any thing and save it as File123 Page 2 is a plane paper and you start drawing with your mouse, hand or stylet User may use some drawing assistance tools to make straight lines, make clean circles etc The user can paint certain area with mouse or can use available tools to fill certain area with a certain color 3 he can open a new file like XL and chose the number of Columns or Rows and use the current program available at Open Office User can insert formulas for calculations etc available in the tools for such programs We will try to avoid 3rd party tools. Either open source or better modified open source tools This is the best we can describe for now.