Yes, it’s technically possible to host a Windows environment inside your Ubuntu 13.04 VPS using a virtual machine (like VirtualBox, KVM, or QEMU), but it's not ideal or efficient, especially on a VPS where resources are usually limited. Hosting a full Windows VM inside a Linux VPS can be very resource-intensive, and Ubuntu 13.04 is also very outdated and no longer supported, which brings major security and compatibility risks.
Here are better options:
Upgrade your VPS to a supported version of Ubuntu or switch to Windows Server VPS hosting directly if you need native support for ASP.NET and want to avoid Mono.
Use .NET Core / .NET 6+ on Linux — it supports C# and ASP.NET Core apps natively without Mono, and it runs well on Ubuntu. It’s modern, cross-platform, and widely used.
If you must use full Windows for legacy ASP.NET apps, it's best to go for a Windows VPS rather than virtualizing inside Linux.