Réponse acceptée !
Bon bein en cherchant un peu dans tout les sens j'ai trouvé, voici la solution avec l'ensemble du web service

Imports System.Web
Imports System.Web.Services
Imports System.Web.Services.Protocols
Imports System.Diagnostics
Imports System.IO

<WebService(Namespace:="http://www.tempuri.org/")> _
<WebServiceBinding(ConformsTo:=WsiProfiles.BasicProfile1_1)> _
<Global.Microsoft.VisualBasic.CompilerServices.DesignerGenerated()> _
Public Class Service
    Inherits System.Web.Services.WebService

    <WebMethod()> _
   Public Function Launch_Server(ByVal exe As String, ByVal args As String) As Boolean
        Dim CryServ As New ProcessStartInfo(exe)
        CryServ.WindowStyle = ProcessWindowStyle.Minimized
        CryServ.Arguments = args
        Process.Start(CryServ)
        Return True
    End Function

    <WebMethod()> _
    Public Function Quit_Server(ByVal servername As String) As Boolean
        Dim CryServ() As Process
        Dim killer As Process
        CryServ = Process.GetProcessesByName(servername)
        For Each killer In CryServ
            killer.CloseMainWindow()
        Next
        Return True
    End Function

    <WebMethod()> _
    Public Function Get_File(ByVal filepath As String) As String
        Return My.Computer.FileSystem.ReadAllText(filepath)
    End Function

    <WebMethod()> _
    Public Function Set_File(ByVal filepath As String, ByVal texte As String) As Boolean
        My.Computer.FileSystem.DeleteFile(filepath)
        My.Computer.FileSystem.WriteAllText(filepath, texte, True)
        Return True
    End Function

End Class