This is my issue. I need to back up one server, that has server 2008 r2 installed. It does have sql server 2008 installed, but I successfully back up our databases every day so that is not an issue. In the event viewer this is the error I am getting about backing up the server:

Backup started at 'DATERANGE' failed as Volume Shadow copy operation failed for backup volumes with following error code '2155348129'. Please rerun backup once issue is resolved.

I ran cmd as admin, typed vssadmin list writers, then hit enter.
This is what failed-
Writer Name- "Microsoft Hyper-v VSS Writer"
State- {8} Failed
Last error- Retryable Error

It has two hyper-v virtual machines on it, and both vm's have more than 5GB of available space on them, so the windows back up isnt failing because of a disk space issue.

But I critically need to do a backup asap. Any help would be much appreciated and I will credit responses with points. Thanks!

Check to make sure you only have 1 vss writer on the server:
"vssadmin list writers"

Multiple writers sometimes cause issues.

You could try a full VSS reset:

net stop "System Event Notification Service"
net stop "Background Intelligent Transfer Service"
net stop "COM+ Event System"
net stop "Microsoft Software Shadow Copy Provider"
net stop "Volume Shadow Copy"
cd /d %windir%\system32
net stop vss
net stop swprv
regsvr32 /s ATL.DLL
regsvr32 /s comsvcs.DLL
regsvr32 /s credui.DLL
regsvr32 /s CRYPTNET.DLL
regsvr32 /s CRYPTUI.DLL
regsvr32 /s dhcpqec.DLL
regsvr32 /s dssenh.DLL
regsvr32 /s eapqec.DLL
regsvr32 /s esscli.DLL
regsvr32 /s FastProx.DLL
regsvr32 /s FirewallAPI.DLL
regsvr32 /s kmsvc.DLL
regsvr32 /s lsmproxy.DLL
regsvr32 /s MSCTF.DLL
regsvr32 /s msi.DLL
regsvr32 /s msxml3.DLL
regsvr32 /s ncprov.DLL
regsvr32 /s ole32.DLL
regsvr32 /s OLEACC.DLL
regsvr32 /s OLEAUT32.DLL
regsvr32 /s PROPSYS.DLL
regsvr32 /s QAgent.DLL
regsvr32 /s qagentrt.DLL
regsvr32 /s QUtil.DLL
regsvr32 /s raschap.DLL
regsvr32 /s RASQEC.DLL
regsvr32 /s rastls.DLL
regsvr32 /s repdrvfs.DLL
regsvr32 /s RPCRT4.DLL
regsvr32 /s rsaenh.DLL
regsvr32 /s SHELL32.DLL
regsvr32 /s shsvcs.DLL
regsvr32 /s /i swprv.DLL
regsvr32 /s tschannel.DLL
regsvr32 /s USERENV.DLL
regsvr32 /s vss_ps.DLL
regsvr32 /s wbemcons.DLL
regsvr32 /s wbemcore.DLL
regsvr32 /s wbemess.DLL
regsvr32 /s wbemsvc.DLL
regsvr32 /s WINHTTP.DLL
regsvr32 /s WINTRUST.DLL
regsvr32 /s wmiprvsd.DLL
regsvr32 /s wmisvc.DLL
regsvr32 /s wmiutils.DLL
regsvr32 /s wuaueng.DLL
sfc /SCANFILE=%windir%\system32\catsrv.DLL
sfc /SCANFILE=%windir%\system32\catsrvut.DLL
sfc /SCANFILE=%windir%\system32\CLBCatQ.DLL
net start "COM+ Event System"

I just got done researching some more into the topic and got my vss writer to be stable again. When the time comes(4pm eastern today) I will be attempting to do another server backup and will report back. But to fix the vss writer error simply do the following steps:
1. On the keyboard, hold the windows key and press R.
2. type services.msc
3. Find Hyper-V Virtual Machine Management and restart the service(Dont worry this does not affect any running vm's)
4.open command prompt under admin priviledges and type vssadmin list writers.

The error should be gone and vss writer state should say Stable, with no errors.

So the issue lied within the vm's. I had to turn them off, then start the backup procedure, then turn them back on once the backup is complete.